diff --git a/NuGet/NuGet.Library/Realm.nuspec b/NuGet/NuGet.Library/Realm.nuspec
index 492ac5b972..258f265685 100755
--- a/NuGet/NuGet.Library/Realm.nuspec
+++ b/NuGet/NuGet.Library/Realm.nuspec
@@ -29,6 +29,8 @@
     <file src="../../Realm.XamarinAndroid/bin/Release/Realm.dll" target="lib\MonoAndroid44" />
     <file src="../../wrappers/build/Release-android/armeabi/libwrappers.so" target="lib\MonoAndroid44\armeabi" />
     <file src="../../wrappers/build/Release-android/armeabi-v7a/libwrappers.so" target="lib\MonoAndroid44\armeabi-v7a" />
+    <file src="../../wrappers/build/Release-android/arm64-v8a/libwrappers.so" target="lib\MonoAndroid44\arm64-v8a" />
     <file src="../../wrappers/build/Release-android/x86/libwrappers.so" target="lib\MonoAndroid44\x86" />
+    <file src="../../wrappers/build/Release-android/x86_64/libwrappers.so" target="lib\MonoAndroid44\x86_64" />
   </files>
 </package>
diff --git a/NuGet/NuGet.Library/Realm.targets b/NuGet/NuGet.Library/Realm.targets
index 2b64eed224..943b892932 100644
--- a/NuGet/NuGet.Library/Realm.targets
+++ b/NuGet/NuGet.Library/Realm.targets
@@ -1,14 +1,26 @@
 <?xml version="1.0"  encoding="utf-8"?>
 <Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
     <ItemGroup>
-        <AndroidNativeLibrary Include="../packages/Realm.0.72.0/lib/MonoAndroid44/armeabi/libwrappers.so">
-            <Link>../packages/Realm.0.72.0/lib/MonoAndroid44/armeabi/libwrappers.so</Link>
+        <AndroidNativeLibrary Include="../packages/Realm.0.72.1/lib/MonoAndroid44/armeabi/libwrappers.so">
+            <Link>../packages/Realm.0.72.1/lib/MonoAndroid44/armeabi/libwrappers.so</Link>
         </AndroidNativeLibrary>
-        <AndroidNativeLibrary Include="../packages/Realm.0.72.0/lib/MonoAndroid44/armeabi-v7a/libwrappers.so">
-            <Link>../packages/Realm.0.72.0/lib/MonoAndroid44/armeabi-v7a/libwrappers.so</Link>
+        <AndroidNativeLibrary Include="../packages/Realm.0.72.1/lib/MonoAndroid44/armeabi-v7a/libwrappers.so">
+            <Link>../packages/Realm.0.72.1/lib/MonoAndroid44/armeabi-v7a/libwrappers.so</Link>
         </AndroidNativeLibrary>
-        <AndroidNativeLibrary Include="../packages/Realm.0.72.0/lib/MonoAndroid44/x86/libwrappers.so">
-            <Link>../packages/Realm.0.72.0/lib/MonoAndroid44/x86/libwrappers.so</Link>
+        <AndroidNativeLibrary Include="../packages/Realm.0.72.1/lib/MonoAndroid44/x86/libwrappers.so">
+            <Link>../packages/Realm.0.72.1/lib/MonoAndroid44/x86/libwrappers.so</Link>
+        </AndroidNativeLibrary>
+<!-- disabled until clarify need and Xamarin support
+        <AndroidNativeLibrary Include="../packages/Realm.0.72.1/lib/MonoAndroid44/mips/libwrappers.so">
+            <Link>../packages/Realm.0.72.1/lib/MonoAndroid44/mips/libwrappers.so</Link>
+        </AndroidNativeLibrary>
+-->        
+<!-- 64bit -->
+        <AndroidNativeLibrary Include="../packages/Realm.0.72.1/lib/MonoAndroid44/arm64-v8a/libwrappers.so">
+            <Link>../packages/Realm.0.72.1/lib/MonoAndroid44/arm64-v8a/libwrappers.so</Link>
+        </AndroidNativeLibrary>
+        <AndroidNativeLibrary Include="../packages/Realm.0.72.1/lib/MonoAndroid44/x86_64/libwrappers.so">
+            <Link>../packages/Realm.0.72.1/lib/MonoAndroid44/x86_64/libwrappers.so</Link>
         </AndroidNativeLibrary>
     </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/README.md b/README.md
index 60cbf89994..3d33034236 100644
--- a/README.md
+++ b/README.md
@@ -46,6 +46,29 @@ We support the current Xamarin _Stable_ and _Beta_ update channels, at the time
 * Xamarin Android version 6.0.0.34
 * Xamarin Studio version 5.10
 
+Building Realm dotnet is not yet automated.
+
+### Building Realm Steps
+
+**Note for Debugging** that the following steps mention building for **Release.** If you are debugging, just substitute **Debug** and you probably also want to choose **Debug | iPhoneSimulator** as a platform.
+
+1. Open a terminal window in the `wrappers` directory
+1. `make clean`
+1. `make all` - this will probably download a current version of core binaries, unless you have built recently. The download and subsequent builds will take some time, depending on your system, as it builds a binary wrapper library for each platform including all Android CPU variations.
+1. Open the `Realm.sln` in `Xamarin Studio` on OS X 
+    1. Choose the Solution `Realm` in the Solution navigator and context menu to `Clean Realm`
+    1. platform popup **Release | Default**
+    1. select `Realm.PCL` project and Build
+    1. select `RealmWeaver.Fody` project and Build
+    1. select platform popup **Release | ARM**
+    1. select `Realm.XamarinAndroid` project and Build
+    1. ensure you have an iOS device attached
+    1. select platform popup **Release | iPhone**
+    1. select `Realm.XamarinIOS` project and Build
+    
+1. If you want to build the NuGet packages, go on from this point and follow the steps in  `internals/RealmDotnetNugetBuild.md`
+
+If you are actively testing code against the Realm source, see also the unit test projects and other tests under the Tests folder.
 
 ## Contributing
 
diff --git a/Realm.XamarinAndroid/Realm.XamarinAndroid.csproj b/Realm.XamarinAndroid/Realm.XamarinAndroid.csproj
index dfcc29e953..206cd85b29 100644
--- a/Realm.XamarinAndroid/Realm.XamarinAndroid.csproj
+++ b/Realm.XamarinAndroid/Realm.XamarinAndroid.csproj
@@ -13,7 +13,7 @@
     <AndroidResgenFile>Resources\Resource.Designer.cs</AndroidResgenFile>
     <GenerateSerializationAssemblies>Off</GenerateSerializationAssemblies>
     <AndroidUseLatestPlatformSdk>True</AndroidUseLatestPlatformSdk>
-    <TargetFrameworkVersion>v4.4</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v6.0</TargetFrameworkVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|ARM' ">
     <DebugSymbols>true</DebugSymbols>
@@ -24,6 +24,7 @@
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <RunCodeAnalysis>false</RunCodeAnalysis>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|ARM' ">
     <Optimize>true</Optimize>
@@ -32,6 +33,7 @@
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <RunCodeAnalysis>false</RunCodeAnalysis>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="Mono.Android" />
diff --git a/Tests/IntegrationTests.XamarinAndroid/IntegrationTests.XamarinAndroid.csproj b/Tests/IntegrationTests.XamarinAndroid/IntegrationTests.XamarinAndroid.csproj
index a55e7c4168..1c71b95391 100644
--- a/Tests/IntegrationTests.XamarinAndroid/IntegrationTests.XamarinAndroid.csproj
+++ b/Tests/IntegrationTests.XamarinAndroid/IntegrationTests.XamarinAndroid.csproj
@@ -14,7 +14,7 @@
     <AndroidApplication>True</AndroidApplication>
     <AndroidUseLatestPlatformSdk>False</AndroidUseLatestPlatformSdk>
     <AssemblyName>IntegrationTests.XamarinAndroid</AssemblyName>
-    <TargetFrameworkVersion>v4.4</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v5.1</TargetFrameworkVersion>
     <AndroidManifest>Properties\AndroidManifest.xml</AndroidManifest>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
@@ -27,6 +27,7 @@
     <WarningLevel>4</WarningLevel>
     <AndroidLinkMode>None</AndroidLinkMode>
     <ConsolePause>false</ConsolePause>
+    <RunCodeAnalysis>false</RunCodeAnalysis>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <DebugType>full</DebugType>
@@ -36,6 +37,7 @@
     <WarningLevel>4</WarningLevel>
     <AndroidUseSharedRuntime>false</AndroidUseSharedRuntime>
     <ConsolePause>false</ConsolePause>
+    <RunCodeAnalysis>false</RunCodeAnalysis>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
diff --git a/Tests/IntegrationTests.XamarinAndroid/Properties/AndroidManifest.xml b/Tests/IntegrationTests.XamarinAndroid/Properties/AndroidManifest.xml
index d5fc02febb..cbe91df4ab 100644
--- a/Tests/IntegrationTests.XamarinAndroid/Properties/AndroidManifest.xml
+++ b/Tests/IntegrationTests.XamarinAndroid/Properties/AndroidManifest.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" android:versionName="1.0" package="IntegrationTests.XamarinAndroid">
-	<uses-sdk />
+	<uses-sdk android:minSdkVersion="10" />
 	<application android:label="IntegrationTests.XamarinAndroid" android:icon="@drawable/icon"></application>
 </manifest>
\ No newline at end of file
diff --git a/Tests/IntegrationTests.XamarinAndroid/Resources/Resource.designer.cs b/Tests/IntegrationTests.XamarinAndroid/Resources/Resource.designer.cs
index 0647c2bd26..2c8181576a 100644
--- a/Tests/IntegrationTests.XamarinAndroid/Resources/Resource.designer.cs
+++ b/Tests/IntegrationTests.XamarinAndroid/Resources/Resource.designer.cs
@@ -2,7 +2,7 @@
 // ------------------------------------------------------------------------------
 //  <autogenerated>
 //      This code was generated by a tool.
-//      Mono Runtime Version: 4.0.30319.17020
+//      Mono Runtime Version: 4.6.57.0
 // 
 //      Changes to this file may cause incorrect behavior and will be lost if 
 //      the code is regenerated.
diff --git a/internals/Realm-dotnet Code Change Diary - Andy Dent.txt b/internals/Realm-dotnet Code Change Diary - Andy Dent.txt
index d625ffa1f6..05668a8fbf 100644
--- a/internals/Realm-dotnet Code Change Diary - Andy Dent.txt	
+++ b/internals/Realm-dotnet Code Change Diary - Andy Dent.txt	
@@ -1583,3 +1583,29 @@ Realm.nuspec
 
 RealmWeaverFody.nuspec
 - set version number as 0.72.0
+
+
+-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+#394 BUILD FOR ARM64, x86_64  with some Android cleanup
+
+wrappers/Makefile
+- incremented NDK command min API from 9 to 10 to match Xamarin
+
+Realm.targets
+- set version number in paths as 0.72.1
+- added arm64-v8a and x86_64 lib build instructions and dependencies
+
+Realm.nuspec
+- added arm64-v8a and x86_64 <file> elements
+  (skipping mips for now until clarify if shipping)
+
+wrappers/jni/Application.mk
+- added x86_64 arm64-v8a to APP_ABI
+  (so they are built into the libs dir)
+
+IntegrationTests.XamarinAndroid
+- Project Options - Build - General
+  set Target Framework to API 22
+- Project Options - Build - Android Application
+  set Minimum Android Version to 2.3 (API 10)
+  
\ No newline at end of file
diff --git a/internals/RealmDotnetNugetBuild.md b/internals/RealmDotnetNugetBuild.md
index 1b79f9ace0..fe6dde53b8 100644
--- a/internals/RealmDotnetNugetBuild.md
+++ b/internals/RealmDotnetNugetBuild.md
@@ -12,17 +12,7 @@ Paths below assume you're starting in the root dir `realm-dotnet` checked out fr
 Building the DLLS
 -----------------
 
-* go into the Wrappers dir in terminal
-* `make clean`
-* `make all`
-* In Xamarin Studio, open`Realm.sln`
-* select platform popup **Release | ARM**
-* select Realm.XamarinAndroid project and Rebuild
-* ensure you have an iOS device attached
-* select platform popup **Release | iPhone**
-* select Realm.XamarinIOS project and Rebuild
-* platform popup **Release | AnyCPU**
-* select Realm.PCL project and Rebuild
+Follow the _Building Realm Steps_ section in `README.md` if you haven't built them already.
 
 Once you have your DLLS, follow these next steps to set version numbers and build NuGet.
 
diff --git a/wrappers/Makefile b/wrappers/Makefile
index d9552de031..a64b91c59a 100644
--- a/wrappers/Makefile
+++ b/wrappers/Makefile
@@ -73,7 +73,7 @@ build/Debug-ios-universal/libwrappers.a: build/Debug-iphoneos/libwrappers.a buil
 
 # Android ====================
 
-android: build/Release-android/armeabi/libwrappers.so build/Release-android/armeabi-v7a/libwrappers.so build/Release-android/x86/libwrappers.so
+android: build/Release-android/armeabi/libwrappers.so build/Release-android/armeabi-v7a/libwrappers.so build/Release-android/x86/libwrappers.so build/Release-android/x86_64/libwrappers.so build/Release-android/arm64-v8a/libwrappers.so build/Release-android/mips/libwrappers.so
 
 core-android: realm-core-android-$(CORE_ANDROID_VER).tar.gz
 	mkdir -p core-android
@@ -84,6 +84,12 @@ core-android: realm-core-android-$(CORE_ANDROID_VER).tar.gz
 	mv core-android/librealm-android-arm-v7a.a core-android/armeabi-v7a/librealm-android.a
 	mkdir -p core-android/x86
 	mv core-android/librealm-android-x86.a core-android/x86/librealm-android.a
+	mkdir -p core-android/arm64-v8a
+	mv core-android/librealm-android-arm64.a core-android/arm64-v8a/librealm-android.a
+	mkdir -p core-android/x86_64
+	mv core-android/librealm-android-x86_64.a core-android/x86_64/librealm-android.a
+	mkdir -p core-android/mips
+	mv core-android/librealm-android-mips.a core-android/mips/librealm-android.a
 	touch core-android
 
 realm-core-android-$(CORE_ANDROID_VER).tar.gz:
@@ -107,8 +113,26 @@ build/Release-android/x86:
 build/Release-android/x86/libwrappers.so: | build/Release-android/x86 libs
 	cp ./libs/x86/librealm-android.so ./build/Release-android/x86/libwrappers.so
 
+build/Release-android/x86_64:
+	mkdir -p build/Release-android/x86_64
+
+build/Release-android/x86_64/libwrappers.so: | build/Release-android/x86_64 libs
+	cp ./libs/x86_64/librealm-android.so ./build/Release-android/x86_64/libwrappers.so
+
+build/Release-android/arm64-v8a:
+	mkdir -p build/Release-android/arm64-v8a
+
+build/Release-android/arm64-v8a/libwrappers.so: | build/Release-android/arm64-v8a libs
+	cp ./libs/arm64-v8a/librealm-android.so ./build/Release-android/arm64-v8a/libwrappers.so
+
+build/Release-android/mips:
+	mkdir -p build/Release-android/mips
+
+build/Release-android/mips/libwrappers.so: | build/Release-android/mips libs
+	cp ./libs/mips/librealm-android.so ./build/Release-android/mips/libwrappers.so
+
 libs: | core-android
-	$(NDK_ROOT)/ndk-build APP_PLATFORM=android-9 V=1
+	$(NDK_ROOT)/ndk-build APP_PLATFORM=android-10 V=1
 	
 
 .PHONY: android
diff --git a/wrappers/jni/Application.mk b/wrappers/jni/Application.mk
index 9cb500794b..f2099141ea 100644
--- a/wrappers/jni/Application.mk
+++ b/wrappers/jni/Application.mk
@@ -1,6 +1,6 @@
 #NDK_TOOLCHAIN_VERSION := clang
 NDK_TOOLCHAIN_VERSION := 4.9
-APP_ABI := armeabi armeabi-v7a x86
+APP_ABI := armeabi armeabi-v7a x86 x86_64 arm64-v8a
 
 #  Enable C++14
 APP_CPPFLAGS += -std=c++14