diff --git a/.github/actions/setup-dotnet/action.yml b/.github/actions/setup-dotnet/action.yml
index 01a84e32..930e7624 100644
--- a/.github/actions/setup-dotnet/action.yml
+++ b/.github/actions/setup-dotnet/action.yml
@@ -12,9 +12,8 @@ runs:
       uses: actions/setup-dotnet@v5
       with:
         dotnet-version: |
-          6.0.x
-          7.0.x
           8.0.x
+          9.0.x
     
     - name: Set up dependency caching for faster builds
       uses: actions/cache@v4
diff --git a/Common.props b/Common.props
index e85e8f5d..1c1ebc0a 100644
--- a/Common.props
+++ b/Common.props
@@ -1,5 +1,5 @@
 <Project>
   <PropertyGroup>
-    <TargetFrameworks>net8.0;net7.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net9.0;net8.0</TargetFrameworks>
   </PropertyGroup>
 </Project>
\ No newline at end of file
diff --git a/Directory.Build.props b/Directory.Build.props
index ff109418..d26b9ce6 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <LangVersion>12.0</LangVersion>
+    <LangVersion>13.0</LangVersion>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <AccelerateBuildsInVisualStudio>true</AccelerateBuildsInVisualStudio>
diff --git a/README.md b/README.md
index 05c2c178..a0ecb941 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ This project contains the source code for the book **Essential C#** by Mark Mich
 
 ## Requirements
 
-- [.NET](https://www.microsoft.com/net/core) - This project is currently tested against .NET 8.0, 7.0, and 6.0.
+- [.NET](https://www.microsoft.com/net/core) - This project is currently tested against .NET 9.0 and 8.0.
 - [Visual Studio](https://visualstudio.microsoft.com/downloads/) - Already contains .NET Core to get up and running. Not to mention, it's a great IDE that makes it easy to get started.
 - [Git](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git) - While not required, a good tool to get used to, and easy way to download this code repository quickly. [GitKraken](https://gitkraken.cello.so/tl7bYaRLgzT) is a great GUI for using Git if you prefer not using the command line. Visual Studio and VSCode also have ever improving git tooling built in.
 
diff --git a/global.json b/global.json
index d4e0b899..00e5df37 100644
--- a/global.json
+++ b/global.json
@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "8.0.0",
+    "version": "9.0.0",
     "rollForward": "latestFeature",
     "allowPrerelease": true
   }
diff --git a/src/Chapter16.Tests/Listing16.15.Tests.cs b/src/Chapter16.Tests/Listing16.15.Tests.cs
index d7ebcceb..035e8696 100644
--- a/src/Chapter16.Tests/Listing16.15.Tests.cs
+++ b/src/Chapter16.Tests/Listing16.15.Tests.cs
@@ -13,7 +13,7 @@ public void SelectingAnonymousTypeFollowingGroupClause()
         string expected = dotnetCoreVersion switch
         {
             // Version <= 5
-            string value when string.Compare(value, "6")<0 => """
+            string value when string.Compare(value, "6") < 0 => """
                         Aggregate, All, Any, Append, AsEnumerable, Average, Cast, Concat, Contains, 
                         Count, DefaultIfEmpty, Distinct, ElementAt, ElementAtOrDefault, Empty, 
                         Except, First, FirstOrDefault, GroupBy, GroupJoin, Intersect, Join, Last, 
@@ -35,8 +35,8 @@ string value when value.StartsWith("6") => """
                     ThenByDescending, ToArray, ToDictionary, ToHashSet, ToList, 
                     ToLookup, TryGetNonEnumeratedCount, Union, UnionBy, Where, Zip, 
                     """,
-            // Version 7
-            _ => """
+            // Version 7-8
+            string value when Version.TryParse(value, out var v) && (v.Major is 7 or 8) => """
                     Aggregate, All, Any, Append, AsEnumerable, Average, Cast, 
                     Chunk, Concat, Contains, Count, DefaultIfEmpty, Distinct, DistinctBy, 
                     ElementAt, ElementAtOrDefault, Empty, Except, ExceptBy, First, 
@@ -47,6 +47,19 @@ string value when value.StartsWith("6") => """
                     SingleOrDefault, Skip, SkipLast, SkipWhile, Sum, Take, TakeLast, 
                     TakeWhile, ThenBy, ThenByDescending, ToArray, ToDictionary, ToHashSet, 
                     ToList, ToLookup, TryGetNonEnumeratedCount, Union, UnionBy, Where, Zip, 
+                    """,
+            // Version 9
+            _ => """
+                    Aggregate, AggregateBy, All, Any, Append, AsEnumerable, Average, Cast, 
+                    Chunk, Concat, Contains, Count, CountBy, DefaultIfEmpty, Distinct, DistinctBy, 
+                    ElementAt, ElementAtOrDefault, Empty, Except, ExceptBy, First, 
+                    FirstOrDefault, GroupBy, GroupJoin, Index, Intersect, IntersectBy, Join, 
+                    Last, LastOrDefault, LongCount, Max, MaxBy, Min, MinBy, OfType, 
+                    Order, OrderBy, OrderByDescending, OrderDescending, Prepend, Range, 
+                    Repeat, Reverse, Select, SelectMany, SequenceEqual, Single, 
+                    SingleOrDefault, Skip, SkipLast, SkipWhile, Sum, Take, TakeLast, 
+                    TakeWhile, ThenBy, ThenByDescending, ToArray, ToDictionary, ToHashSet, 
+                    ToList, ToLookup, TryGetNonEnumeratedCount, Union, UnionBy, Where, Zip, 
                     """
         };