diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 93953a3b90a..352cd83ca94 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -2801,7 +2801,7 @@
         "category": "Message",
         "code": 6099
     },
-    "'package.json' does not have a 'types' or 'main' field.": {
+    "'package.json' does not have a '{0}' field.": {
         "category": "Message",
         "code": 6100
     },
@@ -2949,10 +2949,6 @@
         "category": "Message",
         "code": 6136
     },
-    "No types specified in 'package.json', so returning 'main' value of '{0}'": {
-        "category": "Message",
-        "code": 6137
-    },
     "Property '{0}' is declared but never used.": {
         "category": "Error",
         "code": 6138
diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index 0300ff71ec5..68b043f1439 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -67,40 +67,31 @@ namespace ts {
     }
 
     /** Reads from "main" or "types"/"typings" depending on `extensions`. */
-    function tryReadPackageJsonMainOrTypes(extensions: Extensions, packageJsonPath: string, baseDirectory: string, state: ModuleResolutionState): string {
+    function tryReadPackageJsonFields(readTypes: boolean, packageJsonPath: string, baseDirectory: string, state: ModuleResolutionState): string | undefined {
         const jsonContent = readJson(packageJsonPath, state.host);
+        return readTypes ? tryReadFromField("typings") || tryReadFromField("types") : tryReadFromField("main");
 
-        switch (extensions) {
-            case Extensions.DtsOnly:
-            case Extensions.TypeScript:
-                return tryReadFromField("typings") || tryReadFromField("types");
-
-            case Extensions.JavaScript:
-                if (typeof jsonContent.main === "string") {
-                    if (state.traceEnabled) {
-                        trace(state.host, Diagnostics.No_types_specified_in_package_json_so_returning_main_value_of_0, jsonContent.main);
-                    }
-                    return normalizePath(combinePaths(baseDirectory, jsonContent.main));
-                }
-                return undefined;
-        }
-
-        function tryReadFromField(fieldName: string) {
-            if (hasProperty(jsonContent, fieldName)) {
-                const typesFile = (<any>jsonContent)[fieldName];
-                if (typeof typesFile === "string") {
-                    const typesFilePath = normalizePath(combinePaths(baseDirectory, typesFile));
-                    if (state.traceEnabled) {
-                        trace(state.host, Diagnostics.package_json_has_0_field_1_that_references_2, fieldName, typesFile, typesFilePath);
-                    }
-                    return typesFilePath;
-                }
-                else {
-                    if (state.traceEnabled) {
-                        trace(state.host, Diagnostics.Expected_type_of_0_field_in_package_json_to_be_string_got_1, fieldName, typeof typesFile);
-                    }
+        function tryReadFromField(fieldName: "typings" | "types" | "main"): string | undefined {
+            if (!hasProperty(jsonContent, fieldName)) {
+                if (state.traceEnabled) {
+                    trace(state.host, Diagnostics.package_json_does_not_have_a_0_field, fieldName);
                 }
+                return;
             }
+
+            const fileName = jsonContent[fieldName];
+            if (typeof fileName !== "string") {
+                if (state.traceEnabled) {
+                    trace(state.host, Diagnostics.Expected_type_of_0_field_in_package_json_to_be_string_got_1, fieldName, typeof fileName);
+                }
+                return;
+            }
+
+            const path = normalizePath(combinePaths(baseDirectory, fileName));
+            if (state.traceEnabled) {
+                trace(state.host, Diagnostics.package_json_has_0_field_1_that_references_2, fieldName, fileName, path);
+            }
+            return path;
         }
     }
 
@@ -698,7 +689,8 @@ namespace ts {
         return { resolvedModule: undefined, failedLookupLocations };
 
         function tryResolve(extensions: Extensions): SearchResult<{ resolved: Resolved, isExternalLibraryImport: boolean }> {
-            const resolved = tryLoadModuleUsingOptionalResolutionSettings(extensions, moduleName, containingDirectory, nodeLoadModuleByRelativeName, failedLookupLocations, state);
+            const loader: ResolutionKindSpecificLoader = (extensions, candidate, failedLookupLocations, onlyRecordFailures, state) => nodeLoadModuleByRelativeName(extensions, candidate, failedLookupLocations, onlyRecordFailures, state, /*considerPackageJson*/true);
+            const resolved = tryLoadModuleUsingOptionalResolutionSettings(extensions, moduleName, containingDirectory, loader, failedLookupLocations, state);
             if (resolved) {
                 return toSearchResult({ resolved, isExternalLibraryImport: false });
             }
@@ -713,7 +705,7 @@ namespace ts {
             }
             else {
                 const candidate = normalizePath(combinePaths(containingDirectory, moduleName));
-                const resolved = nodeLoadModuleByRelativeName(extensions, candidate, failedLookupLocations, /*onlyRecordFailures*/ false, state);
+                const resolved = nodeLoadModuleByRelativeName(extensions, candidate, failedLookupLocations, /*onlyRecordFailures*/ false, state, /*considerPackageJson*/true);
                 return resolved && toSearchResult({ resolved, isExternalLibraryImport: false });
             }
         }
@@ -731,7 +723,7 @@ namespace ts {
         return real;
     }
 
-    function nodeLoadModuleByRelativeName(extensions: Extensions, candidate: string, failedLookupLocations: Push<string>, onlyRecordFailures: boolean, state: ModuleResolutionState): Resolved | undefined {
+    function nodeLoadModuleByRelativeName(extensions: Extensions, candidate: string, failedLookupLocations: Push<string>, onlyRecordFailures: boolean, state: ModuleResolutionState, considerPackageJson: boolean): Resolved | undefined {
         if (state.traceEnabled) {
             trace(state.host, Diagnostics.Loading_module_as_file_Slash_folder_candidate_module_location_0_target_file_type_1, candidate, Extensions[extensions]);
         }
@@ -759,7 +751,7 @@ namespace ts {
                 onlyRecordFailures = true;
             }
         }
-        return loadNodeModuleFromDirectory(extensions, candidate, failedLookupLocations, onlyRecordFailures, state);
+        return loadNodeModuleFromDirectory(extensions, candidate, failedLookupLocations, onlyRecordFailures, state, considerPackageJson);
     }
 
     /* @internal */
@@ -835,50 +827,57 @@ namespace ts {
         return undefined;
     }
 
-    function loadNodeModuleFromDirectory(extensions: Extensions, candidate: string, failedLookupLocations: Push<string>, onlyRecordFailures: boolean, state: ModuleResolutionState): Resolved | undefined {
-        const packageJsonPath = pathToPackageJson(candidate);
+    function loadNodeModuleFromDirectory(extensions: Extensions, candidate: string, failedLookupLocations: Push<string>, onlyRecordFailures: boolean, state: ModuleResolutionState, considerPackageJson = true): Resolved | undefined {
         const directoryExists = !onlyRecordFailures && directoryProbablyExists(candidate, state.host);
 
-        if (directoryExists && state.host.fileExists(packageJsonPath)) {
-            if (state.traceEnabled) {
-                trace(state.host, Diagnostics.Found_package_json_at_0, packageJsonPath);
-            }
-            const mainOrTypesFile = tryReadPackageJsonMainOrTypes(extensions, packageJsonPath, candidate, state);
-            if (mainOrTypesFile) {
-                const onlyRecordFailures = !directoryProbablyExists(getDirectoryPath(mainOrTypesFile), state.host);
-                // A package.json "typings" may specify an exact filename, or may choose to omit an extension.
-                const fromExactFile = tryFile(mainOrTypesFile, failedLookupLocations, onlyRecordFailures, state);
-                if (fromExactFile) {
-                    const resolved = fromExactFile && resolvedIfExtensionMatches(extensions, fromExactFile);
-                    if (resolved) {
-                        return resolved;
-                    }
-                    if (state.traceEnabled) {
-                        trace(state.host, Diagnostics.File_0_has_an_unsupported_extension_so_skipping_it, fromExactFile);
-                    }
-                }
-                const resolved = tryAddingExtensions(mainOrTypesFile, Extensions.TypeScript, failedLookupLocations, onlyRecordFailures, state);
-                if (resolved) {
-                    return resolved;
+        if (considerPackageJson) {
+            const packageJsonPath = pathToPackageJson(candidate);
+            if (directoryExists && state.host.fileExists(packageJsonPath)) {
+                const fromPackageJson = loadModuleFromPackageJson(packageJsonPath, extensions, candidate, failedLookupLocations, state);
+                if (fromPackageJson) {
+                    return fromPackageJson;
                 }
             }
             else {
-                if (state.traceEnabled) {
-                    trace(state.host, Diagnostics.package_json_does_not_have_a_types_or_main_field);
+                if (directoryExists && state.traceEnabled) {
+                    trace(state.host, Diagnostics.File_0_does_not_exist, packageJsonPath);
                 }
+                // record package json as one of failed lookup locations - in the future if this file will appear it will invalidate resolution results
+                failedLookupLocations.push(packageJsonPath);
             }
         }
-        else {
-            if (directoryExists && state.traceEnabled) {
-                trace(state.host, Diagnostics.File_0_does_not_exist, packageJsonPath);
-            }
-            // record package json as one of failed lookup locations - in the future if this file will appear it will invalidate resolution results
-            failedLookupLocations.push(packageJsonPath);
-        }
 
         return loadModuleFromFile(extensions, combinePaths(candidate, "index"), failedLookupLocations, !directoryExists, state);
     }
 
+    function loadModuleFromPackageJson(packageJsonPath: string, extensions: Extensions, candidate: string, failedLookupLocations: Push<string>, state: ModuleResolutionState): Resolved | undefined {
+        if (state.traceEnabled) {
+            trace(state.host, Diagnostics.Found_package_json_at_0, packageJsonPath);
+        }
+
+        const file = tryReadPackageJsonFields(extensions !== Extensions.JavaScript, packageJsonPath, candidate, state);
+        if (!file) {
+            return undefined;
+        }
+
+        const onlyRecordFailures = !directoryProbablyExists(getDirectoryPath(file), state.host);
+        const fromFile = tryFile(file, failedLookupLocations, onlyRecordFailures, state);
+        if (fromFile) {
+            const resolved = fromFile && resolvedIfExtensionMatches(extensions, fromFile);
+            if (resolved) {
+                return resolved;
+            }
+            if (state.traceEnabled) {
+                trace(state.host, Diagnostics.File_0_has_an_unsupported_extension_so_skipping_it, fromFile);
+            }
+        }
+
+        // Even if extensions is DtsOnly, we can still look up a .ts file as a result of package.json "types"
+        const nextExtensions = extensions === Extensions.DtsOnly ? Extensions.TypeScript : extensions;
+        // Don't do package.json lookup recursively, because Node.js' package lookup doesn't.
+        return nodeLoadModuleByRelativeName(nextExtensions, file, failedLookupLocations, onlyRecordFailures, state, /*considerPackageJson*/ false);
+    }
+
     /** Resolve from an arbitrarily specified file. Return `undefined` if it has an unsupported extension. */
     function resolvedIfExtensionMatches(extensions: Extensions, path: string): Resolved | undefined {
         const extension = tryGetExtensionFromPath(path);
@@ -1040,7 +1039,6 @@ namespace ts {
         return value !== undefined ? { value } : undefined;
     }
 
-
     /** Calls `callback` on `directory` and every ancestor directory it has, returning the first defined result. */
     function forEachAncestorDirectory<T>(directory: string, callback: (directory: string) => SearchResult<T>): SearchResult<T> {
         while (true) {
diff --git a/tests/baselines/reference/library-reference-12.trace.json b/tests/baselines/reference/library-reference-12.trace.json
index 14e46647d6d..75b53d589ee 100644
--- a/tests/baselines/reference/library-reference-12.trace.json
+++ b/tests/baselines/reference/library-reference-12.trace.json
@@ -5,6 +5,7 @@
     "Directory '/a/b/node_modules' does not exist, skipping all lookups in it.",
     "File '/a/node_modules/jquery.d.ts' does not exist.",
     "Found 'package.json' at '/a/node_modules/jquery/package.json'.",
+    "'package.json' does not have a 'typings' field.",
     "'package.json' has 'types' field 'dist/jquery.d.ts' that references '/a/node_modules/jquery/dist/jquery.d.ts'.",
     "File '/a/node_modules/jquery/dist/jquery.d.ts' exist - use it as a name resolution result.",
     "Resolving real path for '/a/node_modules/jquery/dist/jquery.d.ts', result '/a/node_modules/jquery/dist/jquery.d.ts'",
diff --git a/tests/baselines/reference/library-reference-2.trace.json b/tests/baselines/reference/library-reference-2.trace.json
index 8837f2c9cb1..ef0936a35a2 100644
--- a/tests/baselines/reference/library-reference-2.trace.json
+++ b/tests/baselines/reference/library-reference-2.trace.json
@@ -2,6 +2,7 @@
     "======== Resolving type reference directive 'jquery', containing file '/consumer.ts', root directory '/types'. ========",
     "Resolving with primary search path '/types'",
     "Found 'package.json' at '/types/jquery/package.json'.",
+    "'package.json' does not have a 'typings' field.",
     "'package.json' has 'types' field 'jquery.d.ts' that references '/types/jquery/jquery.d.ts'.",
     "File '/types/jquery/jquery.d.ts' exist - use it as a name resolution result.",
     "Resolving real path for '/types/jquery/jquery.d.ts', result '/types/jquery/jquery.d.ts'",
@@ -9,6 +10,7 @@
     "======== Resolving type reference directive 'jquery', containing file 'test/__inferred type names__.ts', root directory '/types'. ========",
     "Resolving with primary search path '/types'",
     "Found 'package.json' at '/types/jquery/package.json'.",
+    "'package.json' does not have a 'typings' field.",
     "'package.json' has 'types' field 'jquery.d.ts' that references '/types/jquery/jquery.d.ts'.",
     "File '/types/jquery/jquery.d.ts' exist - use it as a name resolution result.",
     "Resolving real path for '/types/jquery/jquery.d.ts', result '/types/jquery/jquery.d.ts'",
diff --git a/tests/baselines/reference/moduleResolutionWithExtensions_unexpected.trace.json b/tests/baselines/reference/moduleResolutionWithExtensions_unexpected.trace.json
index e1b1673b32a..8c820e07e48 100644
--- a/tests/baselines/reference/moduleResolutionWithExtensions_unexpected.trace.json
+++ b/tests/baselines/reference/moduleResolutionWithExtensions_unexpected.trace.json
@@ -6,7 +6,8 @@
     "File '/node_modules/normalize.css.tsx' does not exist.",
     "File '/node_modules/normalize.css.d.ts' does not exist.",
     "Found 'package.json' at '/node_modules/normalize.css/package.json'.",
-    "'package.json' does not have a 'types' or 'main' field.",
+    "'package.json' does not have a 'typings' field.",
+    "'package.json' does not have a 'types' field.",
     "File '/node_modules/normalize.css/index.ts' does not exist.",
     "File '/node_modules/normalize.css/index.tsx' does not exist.",
     "File '/node_modules/normalize.css/index.d.ts' does not exist.",
@@ -15,12 +16,13 @@
     "File '/node_modules/normalize.css.js' does not exist.",
     "File '/node_modules/normalize.css.jsx' does not exist.",
     "Found 'package.json' at '/node_modules/normalize.css/package.json'.",
-    "No types specified in 'package.json', so returning 'main' value of 'normalize.css'",
+    "'package.json' has 'main' field 'normalize.css' that references '/node_modules/normalize.css/normalize.css'.",
     "File '/node_modules/normalize.css/normalize.css' exist - use it as a name resolution result.",
     "File '/node_modules/normalize.css/normalize.css' has an unsupported extension, so skipping it.",
-    "File '/node_modules/normalize.css/normalize.css.ts' does not exist.",
-    "File '/node_modules/normalize.css/normalize.css.tsx' does not exist.",
-    "File '/node_modules/normalize.css/normalize.css.d.ts' does not exist.",
+    "Loading module as file / folder, candidate module location '/node_modules/normalize.css/normalize.css', target file type 'JavaScript'.",
+    "File '/node_modules/normalize.css/normalize.css.js' does not exist.",
+    "File '/node_modules/normalize.css/normalize.css.jsx' does not exist.",
+    "Directory '/node_modules/normalize.css/normalize.css' does not exist, skipping all lookups in it.",
     "File '/node_modules/normalize.css/index.js' does not exist.",
     "File '/node_modules/normalize.css/index.jsx' does not exist.",
     "======== Module name 'normalize.css' was not resolved. ========"
diff --git a/tests/baselines/reference/moduleResolutionWithExtensions_unexpected2.trace.json b/tests/baselines/reference/moduleResolutionWithExtensions_unexpected2.trace.json
index 11dd95ebe45..e550bb41eab 100644
--- a/tests/baselines/reference/moduleResolutionWithExtensions_unexpected2.trace.json
+++ b/tests/baselines/reference/moduleResolutionWithExtensions_unexpected2.trace.json
@@ -6,12 +6,19 @@
     "File '/node_modules/foo.tsx' does not exist.",
     "File '/node_modules/foo.d.ts' does not exist.",
     "Found 'package.json' at '/node_modules/foo/package.json'.",
+    "'package.json' does not have a 'typings' field.",
     "'package.json' has 'types' field 'foo.js' that references '/node_modules/foo/foo.js'.",
     "File '/node_modules/foo/foo.js' exist - use it as a name resolution result.",
     "File '/node_modules/foo/foo.js' has an unsupported extension, so skipping it.",
+    "Loading module as file / folder, candidate module location '/node_modules/foo/foo.js', target file type 'TypeScript'.",
     "File '/node_modules/foo/foo.js.ts' does not exist.",
     "File '/node_modules/foo/foo.js.tsx' does not exist.",
     "File '/node_modules/foo/foo.js.d.ts' does not exist.",
+    "File name '/node_modules/foo/foo.js' has a '.js' extension - stripping it",
+    "File '/node_modules/foo/foo.ts' does not exist.",
+    "File '/node_modules/foo/foo.tsx' does not exist.",
+    "File '/node_modules/foo/foo.d.ts' does not exist.",
+    "Directory '/node_modules/foo/foo.js' does not exist, skipping all lookups in it.",
     "File '/node_modules/foo/index.ts' does not exist.",
     "File '/node_modules/foo/index.tsx' does not exist.",
     "File '/node_modules/foo/index.d.ts' does not exist.",
@@ -20,7 +27,7 @@
     "File '/node_modules/foo.js' does not exist.",
     "File '/node_modules/foo.jsx' does not exist.",
     "Found 'package.json' at '/node_modules/foo/package.json'.",
-    "'package.json' does not have a 'types' or 'main' field.",
+    "'package.json' does not have a 'main' field.",
     "File '/node_modules/foo/index.js' does not exist.",
     "File '/node_modules/foo/index.jsx' does not exist.",
     "======== Module name 'foo' was not resolved. ========"
diff --git a/tests/baselines/reference/packageJsonMain.js b/tests/baselines/reference/packageJsonMain.js
new file mode 100644
index 00000000000..c7f63af27f2
--- /dev/null
+++ b/tests/baselines/reference/packageJsonMain.js
@@ -0,0 +1,34 @@
+//// [tests/cases/conformance/moduleResolution/packageJsonMain.ts] ////
+
+//// [package.json]
+
+{ "main": "oof" }
+
+//// [oof.js]
+module.exports = 0;
+
+//// [package.json]
+{ "main": "rab.js" }
+
+//// [rab.js]
+module.exports = 0;
+
+//// [package.json]
+{ "main": "zab" }
+
+//// [index.js]
+module.exports = 0;
+
+//// [a.ts]
+import foo = require("foo");
+import bar = require("bar");
+import baz = require("baz");
+foo + bar + baz;
+
+
+//// [a.js]
+"use strict";
+var foo = require("foo");
+var bar = require("bar");
+var baz = require("baz");
+foo + bar + baz;
diff --git a/tests/baselines/reference/packageJsonMain.symbols b/tests/baselines/reference/packageJsonMain.symbols
new file mode 100644
index 00000000000..c34c36e8901
--- /dev/null
+++ b/tests/baselines/reference/packageJsonMain.symbols
@@ -0,0 +1,15 @@
+=== /a.ts ===
+import foo = require("foo");
+>foo : Symbol(foo, Decl(a.ts, 0, 0))
+
+import bar = require("bar");
+>bar : Symbol(bar, Decl(a.ts, 0, 28))
+
+import baz = require("baz");
+>baz : Symbol(baz, Decl(a.ts, 1, 28))
+
+foo + bar + baz;
+>foo : Symbol(foo, Decl(a.ts, 0, 0))
+>bar : Symbol(bar, Decl(a.ts, 0, 28))
+>baz : Symbol(baz, Decl(a.ts, 1, 28))
+
diff --git a/tests/baselines/reference/packageJsonMain.trace.json b/tests/baselines/reference/packageJsonMain.trace.json
new file mode 100644
index 00000000000..a167e8dfec6
--- /dev/null
+++ b/tests/baselines/reference/packageJsonMain.trace.json
@@ -0,0 +1,71 @@
+[
+    "======== Resolving module 'foo' from '/a.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module 'foo' from 'node_modules' folder, target file type 'TypeScript'.",
+    "File '/node_modules/foo.ts' does not exist.",
+    "File '/node_modules/foo.tsx' does not exist.",
+    "File '/node_modules/foo.d.ts' does not exist.",
+    "Found 'package.json' at '/node_modules/foo/package.json'.",
+    "'package.json' does not have a 'typings' field.",
+    "'package.json' does not have a 'types' field.",
+    "File '/node_modules/foo/index.ts' does not exist.",
+    "File '/node_modules/foo/index.tsx' does not exist.",
+    "File '/node_modules/foo/index.d.ts' does not exist.",
+    "Directory '/node_modules/@types' does not exist, skipping all lookups in it.",
+    "Loading module 'foo' from 'node_modules' folder, target file type 'JavaScript'.",
+    "File '/node_modules/foo.js' does not exist.",
+    "File '/node_modules/foo.jsx' does not exist.",
+    "Found 'package.json' at '/node_modules/foo/package.json'.",
+    "'package.json' has 'main' field 'oof' that references '/node_modules/foo/oof'.",
+    "File '/node_modules/foo/oof' does not exist.",
+    "Loading module as file / folder, candidate module location '/node_modules/foo/oof', target file type 'JavaScript'.",
+    "File '/node_modules/foo/oof.js' exist - use it as a name resolution result.",
+    "Resolving real path for '/node_modules/foo/oof.js', result '/node_modules/foo/oof.js'",
+    "======== Module name 'foo' was successfully resolved to '/node_modules/foo/oof.js'. ========",
+    "======== Resolving module 'bar' from '/a.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module 'bar' from 'node_modules' folder, target file type 'TypeScript'.",
+    "File '/node_modules/bar.ts' does not exist.",
+    "File '/node_modules/bar.tsx' does not exist.",
+    "File '/node_modules/bar.d.ts' does not exist.",
+    "Found 'package.json' at '/node_modules/bar/package.json'.",
+    "'package.json' does not have a 'typings' field.",
+    "'package.json' does not have a 'types' field.",
+    "File '/node_modules/bar/index.ts' does not exist.",
+    "File '/node_modules/bar/index.tsx' does not exist.",
+    "File '/node_modules/bar/index.d.ts' does not exist.",
+    "Directory '/node_modules/@types' does not exist, skipping all lookups in it.",
+    "Loading module 'bar' from 'node_modules' folder, target file type 'JavaScript'.",
+    "File '/node_modules/bar.js' does not exist.",
+    "File '/node_modules/bar.jsx' does not exist.",
+    "Found 'package.json' at '/node_modules/bar/package.json'.",
+    "'package.json' has 'main' field 'rab.js' that references '/node_modules/bar/rab.js'.",
+    "File '/node_modules/bar/rab.js' exist - use it as a name resolution result.",
+    "Resolving real path for '/node_modules/bar/rab.js', result '/node_modules/bar/rab.js'",
+    "======== Module name 'bar' was successfully resolved to '/node_modules/bar/rab.js'. ========",
+    "======== Resolving module 'baz' from '/a.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module 'baz' from 'node_modules' folder, target file type 'TypeScript'.",
+    "File '/node_modules/baz.ts' does not exist.",
+    "File '/node_modules/baz.tsx' does not exist.",
+    "File '/node_modules/baz.d.ts' does not exist.",
+    "Found 'package.json' at '/node_modules/baz/package.json'.",
+    "'package.json' does not have a 'typings' field.",
+    "'package.json' does not have a 'types' field.",
+    "File '/node_modules/baz/index.ts' does not exist.",
+    "File '/node_modules/baz/index.tsx' does not exist.",
+    "File '/node_modules/baz/index.d.ts' does not exist.",
+    "Directory '/node_modules/@types' does not exist, skipping all lookups in it.",
+    "Loading module 'baz' from 'node_modules' folder, target file type 'JavaScript'.",
+    "File '/node_modules/baz.js' does not exist.",
+    "File '/node_modules/baz.jsx' does not exist.",
+    "Found 'package.json' at '/node_modules/baz/package.json'.",
+    "'package.json' has 'main' field 'zab' that references '/node_modules/baz/zab'.",
+    "File '/node_modules/baz/zab' does not exist.",
+    "Loading module as file / folder, candidate module location '/node_modules/baz/zab', target file type 'JavaScript'.",
+    "File '/node_modules/baz/zab.js' does not exist.",
+    "File '/node_modules/baz/zab.jsx' does not exist.",
+    "File '/node_modules/baz/zab/index.js' exist - use it as a name resolution result.",
+    "Resolving real path for '/node_modules/baz/zab/index.js', result '/node_modules/baz/zab/index.js'",
+    "======== Module name 'baz' was successfully resolved to '/node_modules/baz/zab/index.js'. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/packageJsonMain.types b/tests/baselines/reference/packageJsonMain.types
new file mode 100644
index 00000000000..f30bd95f0e5
--- /dev/null
+++ b/tests/baselines/reference/packageJsonMain.types
@@ -0,0 +1,17 @@
+=== /a.ts ===
+import foo = require("foo");
+>foo : any
+
+import bar = require("bar");
+>bar : any
+
+import baz = require("baz");
+>baz : any
+
+foo + bar + baz;
+>foo + bar + baz : any
+>foo + bar : any
+>foo : any
+>bar : any
+>baz : any
+
diff --git a/tests/baselines/reference/packageJsonMain_isNonRecursive.errors.txt b/tests/baselines/reference/packageJsonMain_isNonRecursive.errors.txt
new file mode 100644
index 00000000000..a886fe3dca5
--- /dev/null
+++ b/tests/baselines/reference/packageJsonMain_isNonRecursive.errors.txt
@@ -0,0 +1,18 @@
+/a.ts(1,22): error TS2307: Cannot find module 'foo'.
+
+
+==== /a.ts (1 errors) ====
+    import foo = require("foo");
+                         ~~~~~
+!!! error TS2307: Cannot find module 'foo'.
+    
+==== /node_modules/foo/package.json (0 errors) ====
+    
+    { "main": "oof" }
+    
+==== /node_modules/foo/oof/package.json (0 errors) ====
+    { "main": "ofo" }
+    
+==== /node_modules/foo/oof/ofo.js (0 errors) ====
+    module.exports = 0;
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/packageJsonMain_isNonRecursive.js b/tests/baselines/reference/packageJsonMain_isNonRecursive.js
new file mode 100644
index 00000000000..edd56b359ee
--- /dev/null
+++ b/tests/baselines/reference/packageJsonMain_isNonRecursive.js
@@ -0,0 +1,18 @@
+//// [tests/cases/conformance/moduleResolution/packageJsonMain_isNonRecursive.ts] ////
+
+//// [package.json]
+
+{ "main": "oof" }
+
+//// [package.json]
+{ "main": "ofo" }
+
+//// [ofo.js]
+module.exports = 0;
+
+//// [a.ts]
+import foo = require("foo");
+
+
+//// [a.js]
+"use strict";
diff --git a/tests/baselines/reference/packageJsonMain_isNonRecursive.trace.json b/tests/baselines/reference/packageJsonMain_isNonRecursive.trace.json
new file mode 100644
index 00000000000..53e1ad25605
--- /dev/null
+++ b/tests/baselines/reference/packageJsonMain_isNonRecursive.trace.json
@@ -0,0 +1,29 @@
+[
+    "======== Resolving module 'foo' from '/a.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module 'foo' from 'node_modules' folder, target file type 'TypeScript'.",
+    "File '/node_modules/foo.ts' does not exist.",
+    "File '/node_modules/foo.tsx' does not exist.",
+    "File '/node_modules/foo.d.ts' does not exist.",
+    "Found 'package.json' at '/node_modules/foo/package.json'.",
+    "'package.json' does not have a 'typings' field.",
+    "'package.json' does not have a 'types' field.",
+    "File '/node_modules/foo/index.ts' does not exist.",
+    "File '/node_modules/foo/index.tsx' does not exist.",
+    "File '/node_modules/foo/index.d.ts' does not exist.",
+    "Directory '/node_modules/@types' does not exist, skipping all lookups in it.",
+    "Loading module 'foo' from 'node_modules' folder, target file type 'JavaScript'.",
+    "File '/node_modules/foo.js' does not exist.",
+    "File '/node_modules/foo.jsx' does not exist.",
+    "Found 'package.json' at '/node_modules/foo/package.json'.",
+    "'package.json' has 'main' field 'oof' that references '/node_modules/foo/oof'.",
+    "File '/node_modules/foo/oof' does not exist.",
+    "Loading module as file / folder, candidate module location '/node_modules/foo/oof', target file type 'JavaScript'.",
+    "File '/node_modules/foo/oof.js' does not exist.",
+    "File '/node_modules/foo/oof.jsx' does not exist.",
+    "File '/node_modules/foo/oof/index.js' does not exist.",
+    "File '/node_modules/foo/oof/index.jsx' does not exist.",
+    "File '/node_modules/foo/index.js' does not exist.",
+    "File '/node_modules/foo/index.jsx' does not exist.",
+    "======== Module name 'foo' was not resolved. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/typingsLookup4.js b/tests/baselines/reference/typingsLookup4.js
index c11bc13c613..bc506a6036b 100644
--- a/tests/baselines/reference/typingsLookup4.js
+++ b/tests/baselines/reference/typingsLookup4.js
@@ -18,19 +18,30 @@ export const k: number;
 //// [lquery.ts]
 export const l = 2;
 
+//// [package.json]
+{ "typings": "mquery" }
+
+//// [index.tsx]
+export const m = 3;
+
 //// [a.ts]
 import { j } from "jquery";
 import { k } from "kquery";
 import { l } from "lquery";
-j + k + l;
+import { m } from "mquery";
+j + k + l + m;
 
 
 //// [lquery.js]
 "use strict";
 exports.l = 2;
+//// [index.js]
+"use strict";
+exports.m = 3;
 //// [a.js]
 "use strict";
 var jquery_1 = require("jquery");
 var kquery_1 = require("kquery");
 var lquery_1 = require("lquery");
-jquery_1.j + kquery_1.k + lquery_1.l;
+var mquery_1 = require("mquery");
+jquery_1.j + kquery_1.k + lquery_1.l + mquery_1.m;
diff --git a/tests/baselines/reference/typingsLookup4.symbols b/tests/baselines/reference/typingsLookup4.symbols
index 144548c6452..9269ee6617d 100644
--- a/tests/baselines/reference/typingsLookup4.symbols
+++ b/tests/baselines/reference/typingsLookup4.symbols
@@ -8,10 +8,14 @@ import { k } from "kquery";
 import { l } from "lquery";
 >l : Symbol(l, Decl(a.ts, 2, 8))
 
-j + k + l;
+import { m } from "mquery";
+>m : Symbol(m, Decl(a.ts, 3, 8))
+
+j + k + l + m;
 >j : Symbol(j, Decl(a.ts, 0, 8))
 >k : Symbol(k, Decl(a.ts, 1, 8))
 >l : Symbol(l, Decl(a.ts, 2, 8))
+>m : Symbol(m, Decl(a.ts, 3, 8))
 
 === /node_modules/@types/jquery/jquery.d.ts ===
 export const j: number;
@@ -25,3 +29,7 @@ export const k: number;
 export const l = 2;
 >l : Symbol(l, Decl(lquery.ts, 0, 12))
 
+=== /node_modules/@types/mquery/mquery/index.tsx ===
+export const m = 3;
+>m : Symbol(m, Decl(index.tsx, 0, 12))
+
diff --git a/tests/baselines/reference/typingsLookup4.trace.json b/tests/baselines/reference/typingsLookup4.trace.json
index 451d68edf28..332d9ffa416 100644
--- a/tests/baselines/reference/typingsLookup4.trace.json
+++ b/tests/baselines/reference/typingsLookup4.trace.json
@@ -21,6 +21,7 @@
     "Found 'package.json' at '/node_modules/@types/kquery/package.json'.",
     "'package.json' has 'typings' field 'kquery' that references '/node_modules/@types/kquery/kquery'.",
     "File '/node_modules/@types/kquery/kquery' does not exist.",
+    "Loading module as file / folder, candidate module location '/node_modules/@types/kquery/kquery', target file type 'TypeScript'.",
     "File '/node_modules/@types/kquery/kquery.ts' does not exist.",
     "File '/node_modules/@types/kquery/kquery.tsx' does not exist.",
     "File '/node_modules/@types/kquery/kquery.d.ts' exist - use it as a name resolution result.",
@@ -36,9 +37,28 @@
     "Found 'package.json' at '/node_modules/@types/lquery/package.json'.",
     "'package.json' has 'typings' field 'lquery' that references '/node_modules/@types/lquery/lquery'.",
     "File '/node_modules/@types/lquery/lquery' does not exist.",
+    "Loading module as file / folder, candidate module location '/node_modules/@types/lquery/lquery', target file type 'TypeScript'.",
     "File '/node_modules/@types/lquery/lquery.ts' exist - use it as a name resolution result.",
     "Resolving real path for '/node_modules/@types/lquery/lquery.ts', result '/node_modules/@types/lquery/lquery.ts'",
     "======== Module name 'lquery' was successfully resolved to '/node_modules/@types/lquery/lquery.ts'. ========",
+    "======== Resolving module 'mquery' from '/a.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module 'mquery' from 'node_modules' folder, target file type 'TypeScript'.",
+    "File '/node_modules/mquery.ts' does not exist.",
+    "File '/node_modules/mquery.tsx' does not exist.",
+    "File '/node_modules/mquery.d.ts' does not exist.",
+    "File '/node_modules/@types/mquery.d.ts' does not exist.",
+    "Found 'package.json' at '/node_modules/@types/mquery/package.json'.",
+    "'package.json' has 'typings' field 'mquery' that references '/node_modules/@types/mquery/mquery'.",
+    "File '/node_modules/@types/mquery/mquery' does not exist.",
+    "Loading module as file / folder, candidate module location '/node_modules/@types/mquery/mquery', target file type 'TypeScript'.",
+    "File '/node_modules/@types/mquery/mquery.ts' does not exist.",
+    "File '/node_modules/@types/mquery/mquery.tsx' does not exist.",
+    "File '/node_modules/@types/mquery/mquery.d.ts' does not exist.",
+    "File '/node_modules/@types/mquery/mquery/index.ts' does not exist.",
+    "File '/node_modules/@types/mquery/mquery/index.tsx' exist - use it as a name resolution result.",
+    "Resolving real path for '/node_modules/@types/mquery/mquery/index.tsx', result '/node_modules/@types/mquery/mquery/index.tsx'",
+    "======== Module name 'mquery' was successfully resolved to '/node_modules/@types/mquery/mquery/index.tsx'. ========",
     "======== Resolving type reference directive 'jquery', containing file '/__inferred type names__.ts', root directory '/node_modules/@types'. ========",
     "Resolving with primary search path '/node_modules/@types'",
     "Found 'package.json' at '/node_modules/@types/jquery/package.json'.",
@@ -51,6 +71,7 @@
     "Found 'package.json' at '/node_modules/@types/kquery/package.json'.",
     "'package.json' has 'typings' field 'kquery' that references '/node_modules/@types/kquery/kquery'.",
     "File '/node_modules/@types/kquery/kquery' does not exist.",
+    "Loading module as file / folder, candidate module location '/node_modules/@types/kquery/kquery', target file type 'TypeScript'.",
     "File '/node_modules/@types/kquery/kquery.ts' does not exist.",
     "File '/node_modules/@types/kquery/kquery.tsx' does not exist.",
     "File '/node_modules/@types/kquery/kquery.d.ts' exist - use it as a name resolution result.",
@@ -61,7 +82,21 @@
     "Found 'package.json' at '/node_modules/@types/lquery/package.json'.",
     "'package.json' has 'typings' field 'lquery' that references '/node_modules/@types/lquery/lquery'.",
     "File '/node_modules/@types/lquery/lquery' does not exist.",
+    "Loading module as file / folder, candidate module location '/node_modules/@types/lquery/lquery', target file type 'TypeScript'.",
     "File '/node_modules/@types/lquery/lquery.ts' exist - use it as a name resolution result.",
     "Resolving real path for '/node_modules/@types/lquery/lquery.ts', result '/node_modules/@types/lquery/lquery.ts'",
-    "======== Type reference directive 'lquery' was successfully resolved to '/node_modules/@types/lquery/lquery.ts', primary: true. ========"
+    "======== Type reference directive 'lquery' was successfully resolved to '/node_modules/@types/lquery/lquery.ts', primary: true. ========",
+    "======== Resolving type reference directive 'mquery', containing file '/__inferred type names__.ts', root directory '/node_modules/@types'. ========",
+    "Resolving with primary search path '/node_modules/@types'",
+    "Found 'package.json' at '/node_modules/@types/mquery/package.json'.",
+    "'package.json' has 'typings' field 'mquery' that references '/node_modules/@types/mquery/mquery'.",
+    "File '/node_modules/@types/mquery/mquery' does not exist.",
+    "Loading module as file / folder, candidate module location '/node_modules/@types/mquery/mquery', target file type 'TypeScript'.",
+    "File '/node_modules/@types/mquery/mquery.ts' does not exist.",
+    "File '/node_modules/@types/mquery/mquery.tsx' does not exist.",
+    "File '/node_modules/@types/mquery/mquery.d.ts' does not exist.",
+    "File '/node_modules/@types/mquery/mquery/index.ts' does not exist.",
+    "File '/node_modules/@types/mquery/mquery/index.tsx' exist - use it as a name resolution result.",
+    "Resolving real path for '/node_modules/@types/mquery/mquery/index.tsx', result '/node_modules/@types/mquery/mquery/index.tsx'",
+    "======== Type reference directive 'mquery' was successfully resolved to '/node_modules/@types/mquery/mquery/index.tsx', primary: true. ========"
 ]
\ No newline at end of file
diff --git a/tests/baselines/reference/typingsLookup4.types b/tests/baselines/reference/typingsLookup4.types
index e3f747ac55d..afa2483a862 100644
--- a/tests/baselines/reference/typingsLookup4.types
+++ b/tests/baselines/reference/typingsLookup4.types
@@ -8,12 +8,17 @@ import { k } from "kquery";
 import { l } from "lquery";
 >l : 2
 
-j + k + l;
+import { m } from "mquery";
+>m : 3
+
+j + k + l + m;
+>j + k + l + m : number
 >j + k + l : number
 >j + k : number
 >j : number
 >k : number
 >l : 2
+>m : 3
 
 === /node_modules/@types/jquery/jquery.d.ts ===
 export const j: number;
@@ -28,3 +33,8 @@ export const l = 2;
 >l : 2
 >2 : 2
 
+=== /node_modules/@types/mquery/mquery/index.tsx ===
+export const m = 3;
+>m : 3
+>3 : 3
+
diff --git a/tests/cases/conformance/moduleResolution/packageJsonMain.ts b/tests/cases/conformance/moduleResolution/packageJsonMain.ts
new file mode 100644
index 00000000000..6bf21cfaa3a
--- /dev/null
+++ b/tests/cases/conformance/moduleResolution/packageJsonMain.ts
@@ -0,0 +1,27 @@
+// @noImplicitReferences: true
+// @currentDirectory: /
+// @traceResolution: true
+
+// @filename: /node_modules/foo/package.json
+{ "main": "oof" }
+
+// @filename: /node_modules/foo/oof.js
+module.exports = 0;
+
+// @filename: /node_modules/bar/package.json
+{ "main": "rab.js" }
+
+// @filename: /node_modules/bar/rab.js
+module.exports = 0;
+
+// @filename: /node_modules/baz/package.json
+{ "main": "zab" }
+
+// @filename: /node_modules/baz/zab/index.js
+module.exports = 0;
+
+// @filename: /a.ts
+import foo = require("foo");
+import bar = require("bar");
+import baz = require("baz");
+foo + bar + baz;
diff --git a/tests/cases/conformance/moduleResolution/packageJsonMain_isNonRecursive.ts b/tests/cases/conformance/moduleResolution/packageJsonMain_isNonRecursive.ts
new file mode 100644
index 00000000000..c6e684b3fe1
--- /dev/null
+++ b/tests/cases/conformance/moduleResolution/packageJsonMain_isNonRecursive.ts
@@ -0,0 +1,15 @@
+// @noImplicitReferences: true
+// @currentDirectory: /
+// @traceResolution: true
+
+// @filename: /node_modules/foo/package.json
+{ "main": "oof" }
+
+// @filename: /node_modules/foo/oof/package.json
+{ "main": "ofo" }
+
+// @filename: /node_modules/foo/oof/ofo.js
+module.exports = 0;
+
+// @filename: /a.ts
+import foo = require("foo");
diff --git a/tests/cases/conformance/typings/typingsLookup4.ts b/tests/cases/conformance/typings/typingsLookup4.ts
index 234090aebad..10317b6084b 100644
--- a/tests/cases/conformance/typings/typingsLookup4.ts
+++ b/tests/cases/conformance/typings/typingsLookup4.ts
@@ -1,6 +1,7 @@
 // @traceResolution: true
 // @noImplicitReferences: true
 // @currentDirectory: /
+// @jsx: react
 // A file extension is optional in typings entries.
 
 // @filename: /tsconfig.json
@@ -24,8 +25,15 @@ export const k: number;
 // @filename: /node_modules/@types/lquery/lquery.ts
 export const l = 2;
 
+// @filename: /node_modules/@types/mquery/package.json
+{ "typings": "mquery" }
+
+// @filename: /node_modules/@types/mquery/mquery/index.tsx
+export const m = 3;
+
 // @filename: /a.ts
 import { j } from "jquery";
 import { k } from "kquery";
 import { l } from "lquery";
-j + k + l;
+import { m } from "mquery";
+j + k + l + m;