diff --git a/CMakeLists.txt b/CMakeLists.txt
index ec44370..9de9576 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -431,6 +431,7 @@ add_subdirectory(src/windows/wslhost)
 add_subdirectory(src/windows/wslrelay)
 add_subdirectory(src/windows/wslinstall)
 add_subdirectory(src/windows/wslaclient)
+add_subdirectory(src/windows/wsladiag)
 
 if (WSL_BUILD_WSL_SETTINGS)
     add_subdirectory(src/windows/libwsl)
diff --git a/msipackage/CMakeLists.txt b/msipackage/CMakeLists.txt
index 7f7bcb1..cc011a9 100644
--- a/msipackage/CMakeLists.txt
+++ b/msipackage/CMakeLists.txt
@@ -3,7 +3,7 @@ set(OUTPUT_PACKAGE ${BIN}/wsl.msi)
 set(PACKAGE_WIX_IN ${CMAKE_CURRENT_LIST_DIR}/package.wix.in)
 set(PACKAGE_WIX ${BIN}/package.wix)
 set(CAB_CACHE ${BIN}/cab)
-set(BINARIES wsl.exe;wslg.exe;wslhost.exe;wslrelay.exe;wslservice.exe;wslserviceproxystub.dll;init;initrd.img;wslinstall.dll;wslaserviceproxystub.dll;wslaservice.exe)
+set(BINARIES wsl.exe;wslg.exe;wslhost.exe;wslrelay.exe;wslservice.exe;wslserviceproxystub.dll;init;initrd.img;wslinstall.dll;wslaserviceproxystub.dll;wslaservice.exe;wsladiag.exe)
 
 if (WSL_BUILD_WSL_SETTINGS)
     list(APPEND BINARIES_DEPENDENCIES "wslsettings/wslsettings.dll;wslsettings/wslsettings.exe;libwsl.dll")
@@ -39,7 +39,7 @@ add_custom_command(
 
 add_custom_target(msipackage DEPENDS ${OUTPUT_PACKAGE})
 set_target_properties(msipackage PROPERTIES EXCLUDE_FROM_ALL FALSE SOURCES ${PACKAGE_WIX_IN})
-add_dependencies(msipackage wsl wslg wslservice wslhost wslrelay wslserviceproxystub init initramfs wslinstall msixgluepackage wslaservice wslaserviceproxystub)
+add_dependencies(msipackage wsl wslg wslservice wslhost wslrelay wslserviceproxystub init initramfs wslinstall msixgluepackage wslaservice wslaserviceproxystub wsladiag)
 
 if (WSL_BUILD_WSL_SETTINGS)
     add_dependencies(msipackage wslsettings libwsl)
@@ -47,7 +47,7 @@ endif()
 
 set_source_files_properties(${OUTPUT_PACKAGE} PROPERTIES GENERATED TRUE)
 
-if (DEFINED WSL_POST_BUILD_COMMAND)
+if (DEFINED WSL_POST_BUILD_COMMAND AND NOT "${WSL_POST_BUILD_COMMAND}" STREQUAL "")
     add_custom_command(
         TARGET msipackage
         POST_BUILD
diff --git a/msipackage/package.wix.in b/msipackage/package.wix.in
index 277fd13..1ceca4e 100644
--- a/msipackage/package.wix.in
+++ b/msipackage/package.wix.in
@@ -27,6 +27,7 @@
                 </File>
 
                 <File Id="wslg.exe" Name="wslg.exe" Source="${BIN}/wslg.exe" />
+                <File Id="wsladiag.exe" Name="wsladiag.exe" Source="${BIN}/wsladiag.exe" />
                 <File Id="wslhost.exe" Name="wslhost.exe" Source="${BIN}/wslhost.exe" />
                 <File Id="wslrelay.exe" Name="wslrelay.exe" Source="${BIN}/wslrelay.exe" />
                 <File Id="wslserviceproxystub.dll" Name="wslserviceproxystub.dll" Source="${BIN}/wslserviceproxystub.dll" />
diff --git a/src/windows/common/WslTelemetry.cpp b/src/windows/common/WslTelemetry.cpp
index 766513d..cac31bb 100644
--- a/src/windows/common/WslTelemetry.cpp
+++ b/src/windows/common/WslTelemetry.cpp
@@ -33,7 +33,7 @@ TRACELOGGING_DEFINE_PROVIDER(
     TraceLoggingOptionMicrosoftTelemetry());
 
 TRACELOGGING_DEFINE_PROVIDER(
-    WslaServiceTelemetryProvider,
+    WslaTelemetryProvider,
     "Microsoft.Windows.Wsla",
     // {0383CE62-8F86-4766-AFB2-9D66A7FB1E90}
     (0x383ce62, 0x8f86, 0x4766, 0xaf, 0xb2, 0x9d, 0x66, 0xa7, 0xfb, 0x1e, 0x90),
diff --git a/src/windows/common/WslTelemetry.h b/src/windows/common/WslTelemetry.h
index 209dfd6..96ee3de 100644
--- a/src/windows/common/WslTelemetry.h
+++ b/src/windows/common/WslTelemetry.h
@@ -28,7 +28,7 @@ extern "C" {
 #endif
 TRACELOGGING_DECLARE_PROVIDER(LxssTelemetryProvider);
 TRACELOGGING_DECLARE_PROVIDER(WslServiceTelemetryProvider);
-TRACELOGGING_DECLARE_PROVIDER(WslaServiceTelemetryProvider);
+TRACELOGGING_DECLARE_PROVIDER(WslaTelemetryProvider);
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/windows/wsladiag/CMakeLists.txt b/src/windows/wsladiag/CMakeLists.txt
new file mode 100644
index 0000000..b135c55
--- /dev/null
+++ b/src/windows/wsladiag/CMakeLists.txt
@@ -0,0 +1,14 @@
+set(SOURCES
+    wsladiag.cpp         
+)
+
+add_executable(wsladiag ${SOURCES})
+
+target_link_libraries(wsladiag
+    ${COMMON_LINK_LIBRARIES}
+    common
+)
+
+target_precompile_headers(wsladiag REUSE_FROM common)
+
+set_target_properties(wsladiag PROPERTIES FOLDER windows)
\ No newline at end of file
diff --git a/src/windows/wsladiag/wsladiag.cpp b/src/windows/wsladiag/wsladiag.cpp
new file mode 100644
index 0000000..d31f382
--- /dev/null
+++ b/src/windows/wsladiag/wsladiag.cpp
@@ -0,0 +1,134 @@
+/*++
+
+Copyright (c) Microsoft. All rights reserved.
+
+Module Name:
+
+    wsladiag.cpp
+
+Abstract:
+
+    Entry point for the wsladiag tool, performs WSL runtime initialization and parses --list/--help.
+
+--*/
+
+#include "precomp.h"
+#include "CommandLine.h"
+#include "wslutil.h"
+#include "wslaservice.h"
+#include "WslSecurity.h"
+
+using namespace wsl::shared;
+namespace wslutil = wsl::windows::common::wslutil;
+
+int wsladiag_main(std::wstring_view commandLine)
+{
+    wslutil::ConfigureCrt();
+    wslutil::InitializeWil();
+
+    WslTraceLoggingInitialize(WslaTelemetryProvider, !wsl::shared::OfficialBuild);
+    auto cleanupTelemetry = wil::scope_exit_log(WI_DIAGNOSTICS_INFO, []() { WslTraceLoggingUninitialize(); });
+
+    wslutil::SetCrtEncoding(_O_U8TEXT);
+
+    auto coInit = wil::CoInitializeEx(COINIT_MULTITHREADED);
+    wslutil::CoInitializeSecurity();
+
+    WSADATA data{};
+    THROW_IF_WIN32_ERROR(WSAStartup(MAKEWORD(2, 2), &data));
+    auto wsaCleanup = wil::scope_exit_log(WI_DIAGNOSTICS_INFO, []() { WSACleanup(); });
+
+    // Command-line parsing using ArgumentParser.
+    ArgumentParser parser(std::wstring{commandLine}, L"wsladiag");
+
+    bool help = false;
+    bool list = false;
+
+    parser.AddArgument(list, L"--list");
+    parser.AddArgument(help, L"--help", L'h'); //  short option is a single wide char
+    parser.Parse();
+
+    auto printUsage = []() {
+        wslutil::PrintMessage(
+            L"wsladiag - WSLA diagnostics tool\n"
+            L"Usage:\n"
+            L"  wsladiag --list    List WSLA sessions\n"
+            L"  wsladiag --help    Show this help",
+            stderr);
+    };
+
+    // If '--help' was requested, print usage and exit.
+    if (help)
+    {
+        printUsage();
+        return 0;
+    }
+
+    if (!list)
+    {
+        // No recognized command → show usage
+        printUsage();
+        return 0;
+    }
+
+    // --list: Call WSLA service COM interface to retrieve and display sessions.
+
+    try
+    {
+        wil::com_ptr<IWSLAUserSession> userSession;
+        THROW_IF_FAILED(CoCreateInstance(__uuidof(WSLAUserSession), nullptr, CLSCTX_LOCAL_SERVER, IID_PPV_ARGS(&userSession)));
+
+        wsl::windows::common::security::ConfigureForCOMImpersonation(userSession.get());
+
+        wil::unique_cotaskmem_array_ptr<WSLA_SESSION_INFORMATION> sessions;
+
+        THROW_IF_FAILED(userSession->ListSessions(&sessions, sessions.size_address<ULONG>()));
+
+        if (sessions.size() == 0)
+        {
+            wslutil::PrintMessage(L"No WSLA sessions found.\n", stdout);
+        }
+        else
+        {
+            wslutil::PrintMessage(std::format(L"Found {} WSLA session{}:\n", sessions.size(), sessions.size() > 1 ? L"s" : L""), stdout);
+
+            wslutil::PrintMessage(L"ID\tCreator PID\tDisplay Name\n", stdout);
+            wslutil::PrintMessage(L"--\t-----------\t------------\n", stdout);
+
+            for (const auto& session : sessions)
+            {
+                const auto* displayName = session.DisplayName;
+
+                wslutil::PrintMessage(std::format(L"{}\t{}\t\t{}\n", session.SessionId, session.CreatorPid, displayName), stdout);
+            }
+        }
+
+        return 0;
+    }
+    catch (...)
+    {
+        const auto hr = wil::ResultFromCaughtException();
+        const std::wstring hrMessage = wslutil::ErrorCodeToString(hr);
+
+        if (!hrMessage.empty())
+        {
+            wslutil::PrintMessage(std::format(L"Error listing WSLA sessions: 0x{:08x} - {}\n", static_cast<unsigned int>(hr), hrMessage), stderr);
+        }
+        else
+        {
+            wslutil::PrintMessage(std::format(L"Error listing WSLA sessions: 0x{:08x}\n", static_cast<unsigned int>(hr)), stderr);
+        }
+
+        return 1;
+    }
+}
+
+int wmain(int /*argc*/, wchar_t** /*argv*/)
+{
+    try
+    {
+        // Use raw Unicode command line so ArgumentParser gets original input.
+        return wsladiag_main(GetCommandLineW());
+    }
+    CATCH_RETURN();
+}
\ No newline at end of file
diff --git a/src/windows/wslaservice/exe/ServiceMain.cpp b/src/windows/wslaservice/exe/ServiceMain.cpp
index 3eeb06c..872ed43 100644
--- a/src/windows/wslaservice/exe/ServiceMain.cpp
+++ b/src/windows/wslaservice/exe/ServiceMain.cpp
@@ -67,7 +67,7 @@ try
 
     // Initialize telemetry.
     // TODO-WSLA: Create a dedicated WSLA provider
-    WslTraceLoggingInitialize(WslaServiceTelemetryProvider, !wsl::shared::OfficialBuild);
+    WslTraceLoggingInitialize(WslaTelemetryProvider, !wsl::shared::OfficialBuild);
 
     WSL_LOG("Service starting", TraceLoggingLevel(WINEVENT_LEVEL_INFO));
 
diff --git a/src/windows/wslaservice/exe/WSLASession.cpp b/src/windows/wslaservice/exe/WSLASession.cpp
index 24a8048..19acca0 100644
--- a/src/windows/wslaservice/exe/WSLASession.cpp
+++ b/src/windows/wslaservice/exe/WSLASession.cpp
@@ -22,8 +22,9 @@ Abstract:
 using wsl::windows::service::wsla::WSLASession;
 using wsl::windows::service::wsla::WSLAVirtualMachine;
 
-WSLASession::WSLASession(const WSLA_SESSION_SETTINGS& Settings, WSLAUserSessionImpl& userSessionImpl) :
-    m_sessionSettings(Settings), m_userSession(&userSessionImpl), m_displayName(Settings.DisplayName)
+WSLASession::WSLASession(ULONG id, const WSLA_SESSION_SETTINGS& Settings, WSLAUserSessionImpl& userSessionImpl) :
+
+    m_id(id), m_sessionSettings(Settings), m_userSession(&userSessionImpl), m_displayName(Settings.DisplayName)
 {
     WSL_LOG("SessionCreated", TraceLoggingValue(m_displayName.c_str(), "DisplayName"));
 
@@ -192,17 +193,22 @@ void WSLASession::ConfigureStorage(const WSLA_SESSION_SETTINGS& Settings)
     deleteVhdOnFailure.release();
 }
 
-HRESULT WSLASession::GetDisplayName(LPWSTR* DisplayName)
-{
-    *DisplayName = wil::make_unique_string<wil::unique_cotaskmem_string>(m_displayName.c_str()).release();
-    return S_OK;
-}
-
 const std::wstring& WSLASession::DisplayName() const
 {
     return m_displayName;
 }
 
+ULONG WSLASession::GetId() const noexcept
+{
+    return m_id;
+}
+
+void WSLASession::CopyDisplayName(_Out_writes_z_(bufferLength) PWSTR buffer, size_t bufferLength) const
+{
+    THROW_HR_IF(E_BOUNDS, m_displayName.size() + 1 > bufferLength);
+    wcscpy_s(buffer, bufferLength, m_displayName.c_str());
+}
+
 HRESULT WSLASession::PullImage(LPCWSTR Image, const WSLA_REGISTRY_AUTHENTICATION_INFORMATION* RegistryInformation, IProgressCallback* ProgressCallback)
 {
     return E_NOTIMPL;
diff --git a/src/windows/wslaservice/exe/WSLASession.h b/src/windows/wslaservice/exe/WSLASession.h
index c34a0d2..a4b3dad 100644
--- a/src/windows/wslaservice/exe/WSLASession.h
+++ b/src/windows/wslaservice/exe/WSLASession.h
@@ -25,12 +25,16 @@ class DECLSPEC_UUID("4877FEFC-4977-4929-A958-9F36AA1892A4") WSLASession
     : public Microsoft::WRL::RuntimeClass<Microsoft::WRL::RuntimeClassFlags<Microsoft::WRL::ClassicCom>, IWSLASession, IFastRundown>
 {
 public:
-    WSLASession(const WSLA_SESSION_SETTINGS& Settings, WSLAUserSessionImpl& userSessionImpl);
+    WSLASession(ULONG id, const WSLA_SESSION_SETTINGS& Settings, WSLAUserSessionImpl& userSessionImpl);
+
     ~WSLASession();
 
-    IFACEMETHOD(GetDisplayName)(LPWSTR* DisplayName) override;
+    ULONG GetId() const noexcept;
+
     const std::wstring& DisplayName() const;
 
+    void CopyDisplayName(_Out_writes_z_(bufferLength) PWSTR buffer, size_t bufferLength) const;
+
     // Image management.
     IFACEMETHOD(PullImage)(_In_ LPCWSTR Image, _In_ const WSLA_REGISTRY_AUTHENTICATION_INFORMATION* RegistryInformation, _In_ IProgressCallback* ProgressCallback) override;
     IFACEMETHOD(ImportImage)(_In_ ULONG Handle, _In_ LPCWSTR Image, _In_ IProgressCallback* ProgressCallback) override;
@@ -54,6 +58,8 @@ public:
     void OnUserSessionTerminating();
 
 private:
+    ULONG m_id = 0;
+
     static WSLAVirtualMachine::Settings CreateVmSettings(const WSLA_SESSION_SETTINGS& Settings);
 
     void ConfigureStorage(const WSLA_SESSION_SETTINGS& Settings);
diff --git a/src/windows/wslaservice/exe/WSLAUserSession.cpp b/src/windows/wslaservice/exe/WSLAUserSession.cpp
index ac2cd3c..7ab4fed 100644
--- a/src/windows/wslaservice/exe/WSLAUserSession.cpp
+++ b/src/windows/wslaservice/exe/WSLAUserSession.cpp
@@ -27,7 +27,7 @@ WSLAUserSessionImpl::~WSLAUserSessionImpl()
     // In case there are still COM references on sessions, signal that the user session is terminating
     // so the sessions are all in a 'terminated' state.
     {
-        std::lock_guard lock(m_lock);
+        std::lock_guard lock(m_wslaSessionsLock);
 
         for (auto& e : m_sessions)
         {
@@ -38,7 +38,7 @@ WSLAUserSessionImpl::~WSLAUserSessionImpl()
 
 void WSLAUserSessionImpl::OnSessionTerminated(WSLASession* Session)
 {
-    std::lock_guard lock(m_lock);
+    std::lock_guard lock(m_wslaSessionsLock);
     WI_VERIFY(m_sessions.erase(Session) == 1);
 }
 
@@ -49,7 +49,8 @@ PSID WSLAUserSessionImpl::GetUserSid() const
 
 HRESULT WSLAUserSessionImpl::CreateSession(const WSLA_SESSION_SETTINGS* Settings, IWSLASession** WslaSession)
 {
-    auto session = wil::MakeOrThrow<WSLASession>(*Settings, *this);
+    ULONG id = m_nextSessionId++;
+    auto session = wil::MakeOrThrow<WSLASession>(id, *Settings, *this);
 
     std::lock_guard lock(m_wslaSessionsLock);
     auto it = m_sessions.emplace(session.Get());
@@ -80,6 +81,26 @@ HRESULT WSLAUserSessionImpl::OpenSessionByName(LPCWSTR DisplayName, IWSLASession
     return HRESULT_FROM_WIN32(ERROR_NOT_FOUND);
 }
 
+HRESULT wsl::windows::service::wsla::WSLAUserSessionImpl::ListSessions(_Out_ WSLA_SESSION_INFORMATION** Sessions, _Out_ ULONG* SessionsCount)
+{
+    std::lock_guard lock(m_wslaSessionsLock);
+    auto output = wil::make_unique_cotaskmem<WSLA_SESSION_INFORMATION[]>(m_sessions.size());
+
+    size_t index = 0;
+    for (auto* session : m_sessions)
+    {
+        output[index].SessionId = session->GetId();
+        output[index].CreatorPid = 0; // placeholder until we populate this later
+
+        session->CopyDisplayName(output[index].DisplayName, _countof(output[index].DisplayName));
+
+        ++index;
+    }
+    *Sessions = output.release();
+    *SessionsCount = static_cast<ULONG>(m_sessions.size());
+    return S_OK;
+}
+
 wsl::windows::service::wsla::WSLAUserSession::WSLAUserSession(std::weak_ptr<WSLAUserSessionImpl>&& Session) :
     m_session(std::move(Session))
 {
@@ -105,9 +126,20 @@ try
 CATCH_RETURN();
 
 HRESULT wsl::windows::service::wsla::WSLAUserSession::ListSessions(WSLA_SESSION_INFORMATION** Sessions, ULONG* SessionsCount)
+try
 {
-    return E_NOTIMPL;
+    if (!Sessions || !SessionsCount)
+    {
+        return E_INVALIDARG;
+    }
+
+    auto session = m_session.lock();
+    RETURN_HR_IF(RPC_E_DISCONNECTED, !session);
+
+    RETURN_IF_FAILED(session->ListSessions(Sessions, SessionsCount));
+    return S_OK;
 }
+CATCH_RETURN();
 
 HRESULT wsl::windows::service::wsla::WSLAUserSession::OpenSession(ULONG Id, IWSLASession** Session)
 {
diff --git a/src/windows/wslaservice/exe/WSLAUserSession.h b/src/windows/wslaservice/exe/WSLAUserSession.h
index be8c9a5..1ef6b13 100644
--- a/src/windows/wslaservice/exe/WSLAUserSession.h
+++ b/src/windows/wslaservice/exe/WSLAUserSession.h
@@ -15,6 +15,10 @@ Abstract:
 #pragma once
 #include "WSLAVirtualMachine.h"
 #include "WSLASession.h"
+#include <atomic>
+#include <vector>
+#include <mutex>
+#include <unordered_set>
 
 namespace wsl::windows::service::wsla {
 
@@ -31,14 +35,15 @@ public:
 
     HRESULT CreateSession(const WSLA_SESSION_SETTINGS* Settings, IWSLASession** WslaSession);
     HRESULT OpenSessionByName(_In_ LPCWSTR DisplayName, _Out_ IWSLASession** Session);
+    HRESULT ListSessions(_Out_ WSLA_SESSION_INFORMATION** Sessions, _Out_ ULONG* SessionsCount);
 
     void OnSessionTerminated(WSLASession* Session);
 
 private:
     wil::unique_tokeninfo_ptr<TOKEN_USER> m_tokenInfo;
 
+    std::atomic<ULONG> m_nextSessionId{1};
     std::recursive_mutex m_wslaSessionsLock;
-    std::recursive_mutex m_lock;
 
     // TODO-WSLA: Consider using a weak_ptr to easily destroy when the last client reference is released.
     std::unordered_set<WSLASession*> m_sessions;
diff --git a/src/windows/wslaservice/inc/wslaservice.idl b/src/windows/wslaservice/inc/wslaservice.idl
index 957882c..2e31b20 100644
--- a/src/windows/wslaservice/inc/wslaservice.idl
+++ b/src/windows/wslaservice/inc/wslaservice.idl
@@ -299,15 +299,14 @@ interface IWSLASession : IUnknown
     HRESULT Shutdown([in] ULONG TimeoutMs);
 
      // To be deleted.
-    HRESULT GetDisplayName([out] LPWSTR* DisplayName);
     HRESULT GetVirtualMachine([out] IWSLAVirtualMachine **VirtualMachine);
 }
 
 struct WSLA_SESSION_INFORMATION
 {
-    ULONG Id;
+    ULONG SessionId;
     DWORD CreatorPid;
-    LPSTR DisplayName;
+    wchar_t DisplayName[256];
 };
 
 [