diff --git a/src/coreclr/debug/daccess/dacimpl.h b/src/coreclr/debug/daccess/dacimpl.h
index 0d3ab3ad7bd18..cec666bc02bc1 100644
--- a/src/coreclr/debug/daccess/dacimpl.h
+++ b/src/coreclr/debug/daccess/dacimpl.h
@@ -1061,7 +1061,7 @@ class ClrDataAccess
     virtual HRESULT STDMETHODCALLTYPE GetAppDomainData(CLRDATA_ADDRESS addr, struct DacpAppDomainData *data);
     virtual HRESULT STDMETHODCALLTYPE GetAppDomainName(CLRDATA_ADDRESS addr, unsigned int count, _Inout_updates_z_(count) WCHAR *name, unsigned int *pNeeded);
     virtual HRESULT STDMETHODCALLTYPE GetAssemblyList(CLRDATA_ADDRESS appDomain, int count, CLRDATA_ADDRESS values[], int *fetched);
-    virtual HRESULT STDMETHODCALLTYPE GetAssemblyData(CLRDATA_ADDRESS baseDomainPtr, CLRDATA_ADDRESS assembly, struct DacpAssemblyData *data);
+    virtual HRESULT STDMETHODCALLTYPE GetAssemblyData(CLRDATA_ADDRESS domainPtr, CLRDATA_ADDRESS assembly, struct DacpAssemblyData *data);
     virtual HRESULT STDMETHODCALLTYPE GetAssemblyName(CLRDATA_ADDRESS assembly, unsigned int count, _Inout_updates_z_(count) WCHAR *name, unsigned int *pNeeded);
     virtual HRESULT STDMETHODCALLTYPE GetThreadData(CLRDATA_ADDRESS thread, struct DacpThreadData *data);
     virtual HRESULT STDMETHODCALLTYPE GetThreadFromThinlockID(UINT thinLockId, CLRDATA_ADDRESS *pThread);
diff --git a/src/coreclr/debug/daccess/request.cpp b/src/coreclr/debug/daccess/request.cpp
index 2be13b91e98aa..5e73d02325112 100644
--- a/src/coreclr/debug/daccess/request.cpp
+++ b/src/coreclr/debug/daccess/request.cpp
@@ -2834,19 +2834,17 @@ ClrDataAccess::GetAppDomainData(CLRDATA_ADDRESS addr, struct DacpAppDomainData *
     }
     else
     {
-        PTR_BaseDomain pBaseDomain = PTR_BaseDomain(TO_TADDR(addr));
-
         ZeroMemory(appdomainData, sizeof(DacpAppDomainData));
-        appdomainData->AppDomainPtr = PTR_CDADDR(pBaseDomain);
+        appdomainData->AppDomainPtr = addr;
         PTR_LoaderAllocator pLoaderAllocator = SystemDomain::GetGlobalLoaderAllocator();
         appdomainData->pHighFrequencyHeap = HOST_CDADDR(pLoaderAllocator->GetHighFrequencyHeap());
         appdomainData->pLowFrequencyHeap = HOST_CDADDR(pLoaderAllocator->GetLowFrequencyHeap());
         appdomainData->pStubHeap = HOST_CDADDR(pLoaderAllocator->GetStubHeap());
         appdomainData->appDomainStage = STAGE_OPEN;
 
-        if (pBaseDomain->IsAppDomain())
+        if (addr != HOST_CDADDR(SystemDomain::System()))
         {
-            AppDomain * pAppDomain = pBaseDomain->AsAppDomain();
+            PTR_AppDomain pAppDomain = PTR_AppDomain(TO_TADDR(addr));
             appdomainData->DomainLocalBlock = 0;
             appdomainData->pDomainLocalModules = 0;
 
@@ -2963,15 +2961,19 @@ ClrDataAccess::GetAssemblyList(CLRDATA_ADDRESS addr, int count, CLRDATA_ADDRESS
 
     SOSDacEnter();
 
-    BaseDomain* pBaseDomain = PTR_BaseDomain(TO_TADDR(addr));
-
-    int n=0;
-    if (pBaseDomain->IsAppDomain())
+    if (addr == HOST_CDADDR(SystemDomain::System()))
+    {
+        // We shouldn't be asking for the assemblies in SystemDomain
+        hr = E_INVALIDARG;
+    }
+    else
     {
-        AppDomain::AssemblyIterator i = pBaseDomain->AsAppDomain()->IterateAssembliesEx(
+        PTR_AppDomain pAppDomain = PTR_AppDomain(TO_TADDR(addr));
+        AppDomain::AssemblyIterator i = pAppDomain->IterateAssembliesEx(
             (AssemblyIterationFlags)(kIncludeLoading | kIncludeLoaded | kIncludeExecution));
         CollectibleAssemblyHolder<DomainAssembly *> pDomainAssembly;
 
+        int n = 0;
         if (values)
         {
             while (i.Next(pDomainAssembly.This()) && (n < count))
@@ -2994,13 +2996,6 @@ ClrDataAccess::GetAssemblyList(CLRDATA_ADDRESS addr, int count, CLRDATA_ADDRESS
         if (pNeeded)
             *pNeeded = n;
     }
-    else
-    {
-        // The only other type of BaseDomain is the SystemDomain, and we shouldn't be asking
-        // for the assemblies in it.
-        _ASSERTE(false);
-        hr = E_INVALIDARG;
-    }
 
     SOSDacLeave();
     return hr;
@@ -3040,10 +3035,9 @@ ClrDataAccess::GetAppDomainName(CLRDATA_ADDRESS addr, unsigned int count, _Inout
 {
     SOSDacEnter();
 
-    PTR_BaseDomain pBaseDomain = PTR_BaseDomain(TO_TADDR(addr));
-    if (!pBaseDomain->IsAppDomain())
+    if (addr == HOST_CDADDR(SystemDomain::System()))
     {
-        // Shared domain and SystemDomain don't have this field.
+        // SystemDomain doesn't have this field.
         if (pNeeded)
             *pNeeded = 1;
         if (name)
@@ -3051,8 +3045,7 @@ ClrDataAccess::GetAppDomainName(CLRDATA_ADDRESS addr, unsigned int count, _Inout
     }
     else
     {
-        AppDomain* pAppDomain = pBaseDomain->AsAppDomain();
-
+        PTR_AppDomain pAppDomain = PTR_AppDomain(TO_TADDR(addr));
         if (!pAppDomain->m_friendlyName.IsEmpty())
         {
             if (!pAppDomain->m_friendlyName.DacGetUnicode(count, name, pNeeded))
@@ -3103,9 +3096,9 @@ ClrDataAccess::GetAppDomainConfigFile(CLRDATA_ADDRESS appDomain, int count,
 }
 
 HRESULT
-ClrDataAccess::GetAssemblyData(CLRDATA_ADDRESS cdBaseDomainPtr, CLRDATA_ADDRESS assembly, struct DacpAssemblyData *assemblyData)
+ClrDataAccess::GetAssemblyData(CLRDATA_ADDRESS domain, CLRDATA_ADDRESS assembly, struct DacpAssemblyData *assemblyData)
 {
-    if (assembly == (CLRDATA_ADDRESS)NULL && cdBaseDomainPtr == (CLRDATA_ADDRESS)NULL)
+    if (assembly == (CLRDATA_ADDRESS)NULL && domain == (CLRDATA_ADDRESS)NULL)
     {
         return E_INVALIDARG;
     }
@@ -3117,14 +3110,9 @@ ClrDataAccess::GetAssemblyData(CLRDATA_ADDRESS cdBaseDomainPtr, CLRDATA_ADDRESS
     // Make sure conditionally-assigned fields like AssemblySecDesc, LoadContext, etc. are zeroed
     ZeroMemory(assemblyData, sizeof(DacpAssemblyData));
 
-    // If the specified BaseDomain is an AppDomain, get a pointer to it
-    AppDomain * pDomain = NULL;
-    if (cdBaseDomainPtr != (CLRDATA_ADDRESS)NULL)
+    if (domain != (CLRDATA_ADDRESS)NULL)
     {
-        assemblyData->BaseDomainPtr = cdBaseDomainPtr;
-        PTR_BaseDomain baseDomain = PTR_BaseDomain(TO_TADDR(cdBaseDomainPtr));
-        if( baseDomain->IsAppDomain() )
-            pDomain = baseDomain->AsAppDomain();
+        assemblyData->DomainPtr = domain;
     }
 
     assemblyData->AssemblyPtr = HOST_CDADDR(pAssembly);
diff --git a/src/coreclr/inc/dacprivate.h b/src/coreclr/inc/dacprivate.h
index 305029634406c..62821f71395af 100644
--- a/src/coreclr/inc/dacprivate.h
+++ b/src/coreclr/inc/dacprivate.h
@@ -425,11 +425,11 @@ enum DacpAppDomainDataStage {
     STAGE_CLOSED
 };
 
-// Information about a BaseDomain (AppDomain, SharedDomain or SystemDomain).
+// Information about an AppDomain or SystemDomain.
 // For types other than AppDomain, some fields (like dwID, DomainLocalBlock, etc.) will be 0/null.
 struct MSLAYOUT DacpAppDomainData
 {
-    // The pointer to the BaseDomain (not necessarily an AppDomain).
+    // The pointer to the AppDomain or SystemDomain.
     // It's useful to keep this around in the structure
     CLRDATA_ADDRESS AppDomainPtr = 0;
     CLRDATA_ADDRESS AppSecDesc = 0;
@@ -455,7 +455,7 @@ struct MSLAYOUT DacpAssemblyData
     CLRDATA_ADDRESS AssemblyPtr = 0; //useful to have
     CLRDATA_ADDRESS ClassLoader = 0;
     CLRDATA_ADDRESS ParentDomain = 0;
-    CLRDATA_ADDRESS BaseDomainPtr = 0;
+    CLRDATA_ADDRESS DomainPtr = 0;
     CLRDATA_ADDRESS AssemblySecDesc = 0;
     BOOL isDynamic = FALSE;
     UINT ModuleCount = FALSE;
@@ -463,9 +463,9 @@ struct MSLAYOUT DacpAssemblyData
     BOOL isDomainNeutral = FALSE; // Always false, preserved for backward compatibility
     DWORD dwLocationFlags = 0;
 
-    HRESULT Request(ISOSDacInterface *sos, CLRDATA_ADDRESS addr, CLRDATA_ADDRESS baseDomainPtr)
+    HRESULT Request(ISOSDacInterface *sos, CLRDATA_ADDRESS addr, CLRDATA_ADDRESS domainPtr)
     {
-        return sos->GetAssemblyData(baseDomainPtr, addr, this);
+        return sos->GetAssemblyData(domainPtr, addr, this);
     }
 
     HRESULT Request(ISOSDacInterface *sos, CLRDATA_ADDRESS addr)
diff --git a/src/coreclr/vm/appdomain.cpp b/src/coreclr/vm/appdomain.cpp
index 4478a450df9d5..287823cac17f6 100644
--- a/src/coreclr/vm/appdomain.cpp
+++ b/src/coreclr/vm/appdomain.cpp
@@ -1546,15 +1546,15 @@ void SystemDomain::NotifyProfilerStartup()
 
     {
         BEGIN_PROFILER_CALLBACK(CORProfilerTrackAppDomainLoads());
-        _ASSERTE(System()->DefaultDomain());
-        (&g_profControlBlock)->AppDomainCreationStarted((AppDomainID) System()->DefaultDomain());
+        _ASSERTE(AppDomain::GetCurrentDomain());
+        (&g_profControlBlock)->AppDomainCreationStarted((AppDomainID) AppDomain::GetCurrentDomain());
         END_PROFILER_CALLBACK();
     }
 
     {
         BEGIN_PROFILER_CALLBACK(CORProfilerTrackAppDomainLoads());
-        _ASSERTE(System()->DefaultDomain());
-        (&g_profControlBlock)->AppDomainCreationFinished((AppDomainID) System()->DefaultDomain(), S_OK);
+        _ASSERTE(AppDomain::GetCurrentDomain());
+        (&g_profControlBlock)->AppDomainCreationFinished((AppDomainID) AppDomain::GetCurrentDomain(), S_OK);
         END_PROFILER_CALLBACK();
     }
 }
@@ -1585,15 +1585,15 @@ HRESULT SystemDomain::NotifyProfilerShutdown()
 
     {
         BEGIN_PROFILER_CALLBACK(CORProfilerTrackAppDomainLoads());
-        _ASSERTE(System()->DefaultDomain());
-        (&g_profControlBlock)->AppDomainShutdownStarted((AppDomainID) System()->DefaultDomain());
+        _ASSERTE(AppDomain::GetCurrentDomain());
+        (&g_profControlBlock)->AppDomainShutdownStarted((AppDomainID) AppDomain::GetCurrentDomain());
         END_PROFILER_CALLBACK();
     }
 
     {
         BEGIN_PROFILER_CALLBACK(CORProfilerTrackAppDomainLoads());
-        _ASSERTE(System()->DefaultDomain());
-        (&g_profControlBlock)->AppDomainShutdownFinished((AppDomainID) System()->DefaultDomain(), S_OK);
+        _ASSERTE(AppDomain::GetCurrentDomain());
+        (&g_profControlBlock)->AppDomainShutdownFinished((AppDomainID) AppDomain::GetCurrentDomain(), S_OK);
         END_PROFILER_CALLBACK();
     }
     return (S_OK);
diff --git a/src/coreclr/vm/proftoeeinterfaceimpl.cpp b/src/coreclr/vm/proftoeeinterfaceimpl.cpp
index e99273beb5d13..614a6036fdf8a 100644
--- a/src/coreclr/vm/proftoeeinterfaceimpl.cpp
+++ b/src/coreclr/vm/proftoeeinterfaceimpl.cpp
@@ -3148,9 +3148,9 @@ HRESULT ProfToEEInterfaceImpl::GetAppDomainStaticAddress(ClassID classId,
         return E_INVALIDARG;
     }
 
-    // Some domains, like the system domain, aren't APP domains, and thus don't contain any
+    // The system domain isn't an APP domain and thus doesn't contain any
     // statics.  See if the profiler is trying to be naughty.
-    if (!((BaseDomain*) appDomainId)->IsAppDomain())
+    if (appDomainId == (AppDomainID)SystemDomain::System())
     {
         return E_INVALIDARG;
     }
@@ -3382,9 +3382,9 @@ HRESULT ProfToEEInterfaceImpl::GetThreadStaticAddress2(ClassID classId,
         return E_INVALIDARG;
     }
 
-    // Some domains, like the system domain, aren't APP domains, and thus don't contain any
+    // The system domain isn't an APP domain and thus doesn't contain any
     // statics.  See if the profiler is trying to be naughty.
-    if (!((BaseDomain*) appDomainId)->IsAppDomain())
+    if (appDomainId == (AppDomainID)SystemDomain::System())
     {
         return E_INVALIDARG;
     }
@@ -5479,25 +5479,8 @@ HRESULT ProfToEEInterfaceImpl::GetAppDomainInfo(AppDomainID appDomainId,
         return E_INVALIDARG;
     }
 
-    BaseDomain   *pDomain;            // Internal data structure.
     HRESULT     hr = S_OK;
 
-    // <TODO>@todo:
-    // Right now, this ID is not a true AppDomain, since we use the old
-    // AppDomain/SystemDomain model in the profiling API.  This means that
-    // the profiler exposes the SharedDomain and the SystemDomain to the
-    // outside world. It's not clear whether this is actually the right thing
-    // to do or not. - seantrow
-    //
-    // Postponed to V2.
-    // </TODO>
-
-    pDomain = (BaseDomain *) appDomainId;
-
-    // Make sure they've passed in a valid appDomainId
-    if (pDomain == NULL)
-        return (E_INVALIDARG);
-
     // Pick sensible defaults.
     if (pcchName)
         *pcchName = 0;
@@ -5507,10 +5490,10 @@ HRESULT ProfToEEInterfaceImpl::GetAppDomainInfo(AppDomainID appDomainId,
         *pProcessId = 0;
 
     LPCWSTR szFriendlyName;
-    if (pDomain == SystemDomain::System())
+    if (appDomainId == (AppDomainID)SystemDomain::System())
         szFriendlyName = g_pwBaseLibrary;
     else
-        szFriendlyName = ((AppDomain*)pDomain)->GetFriendlyNameForDebugger();
+        szFriendlyName = ((AppDomain*)appDomainId)->GetFriendlyNameForDebugger();
 
     if (szFriendlyName != NULL)
     {