diff --git a/src/Tasks/Common/Resources/Strings.resx b/src/Tasks/Common/Resources/Strings.resx
index d4fc63f0c196..4e7216b894e6 100644
--- a/src/Tasks/Common/Resources/Strings.resx
+++ b/src/Tasks/Common/Resources/Strings.resx
@@ -891,4 +891,8 @@ You may need to build the project on another operating system or architecture, o
     <value>NETSDK1196: The SDK does not support ahead-of-time compilation. Set the PublishAot property to false.</value>
     <comment>{StrBegin="NETSDK1196: "}</comment>
   </data>
+  <data name="RuntimeIdentifierWillNoLongerImplySelfContained" xml:space="preserve">
+    <value>NETSDK1198: In projects with TargetFrameworks >= 8.0, RuntimeIdentifier no longer automatically gives a SelfContained app. To preserve a project's current behavior after upgrading to 8.0, consider setting SelfContained explicitly.</value>
+    <comment>{StrBegin="NETSDK1198: "}</comment>
+  </data>
 </root>
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.RuntimeIdentifierInference.targets b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.RuntimeIdentifierInference.targets
index 73c6643b6053..3bde13f8bf9d 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.RuntimeIdentifierInference.targets
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.RuntimeIdentifierInference.targets
@@ -149,7 +149,9 @@ Copyright (c) .NET Foundation. All rights reserved.
     <_SelfContainedWasSpecified Condition="'$(SelfContained)' != ''">true</_SelfContainedWasSpecified>
   </PropertyGroup>
   <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' and '$(HasRuntimeOutput)' == 'true'">
-    <SelfContained Condition="'$(SelfContained)' == '' and '$(RuntimeIdentifier)' != ''">true</SelfContained>
+    <!-- Breaking change below! Projects with 8.0+ TFMS will no longer have RuntimeIdentifier imply SelfContained. -->
+    <SelfContained Condition="'$(SelfContained)' == '' and '$(RuntimeIdentifier)' != '' and
+                              '$(_TargetFrameworkVersionWithoutV)' &lt; '8.0'">true</SelfContained>
     <SelfContained Condition="'$(SelfContained)' == ''">false</SelfContained>
     <_RuntimeIdentifierUsesAppHost Condition="$(RuntimeIdentifier.StartsWith('ios')) or $(RuntimeIdentifier.StartsWith('tvos')) or $(RuntimeIdentifier.StartsWith('maccatalyst')) or $(RuntimeIdentifier.StartsWith('android')) or $(RuntimeIdentifier.StartsWith('browser'))">false</_RuntimeIdentifierUsesAppHost>
     <_RuntimeIdentifierUsesAppHost Condition="'$(_RuntimeIdentifierUsesAppHost)' == ''">true</_RuntimeIdentifierUsesAppHost>
@@ -222,10 +224,15 @@ Copyright (c) .NET Foundation. All rights reserved.
          because we do not want the behavior to be a breaking change compared to version 3.0 -->
 
     <NETSdkWarning Condition="'$(PublishReadyToRun)' == 'true' and '$(_TargetFrameworkVersionWithoutV)' &lt; '3.0'"
-                   ResourceName="PublishReadyToRunRequiresVersion30" />
+                 ResourceName="PublishReadyToRunRequiresVersion30" />
 
     <NETSdkWarning Condition="'$(PublishTrimmed)' == 'true' and '$(_TargetFrameworkVersionWithoutV)' &lt; '3.0'"
-                   ResourceName="PublishTrimmedRequiresVersion30" />
+                 ResourceName="PublishTrimmedRequiresVersion30" />
+
+    <!-- Previously, RuntimeIdentifier (RID) implied SelfContained (SC). A breaking change in 8.0 made it so RID did not activate SC by default.
+         So we warn older TFM users before they upgrade to TFM 8.0 or above that they need to add <SelfContained>true</SelfContained> now to keep the same behavior.-->
+    <NETSdkWarning Condition="'$(RuntimeIdentifier)' != '' and '$(_TargetFrameworkVersionWithoutV)' != '' and '$(_TargetFrameworkVersionWithoutV)' &lt; '8.0' and '$(_SelfContainedWasSpecified)' != 'true' and '$(SelfContained)' == ''"
+                 ResourceName="RuntimeIdentifierWillNoLongerImplySelfContained" />
 
     <!-- Generate Trimming warnings for WinForms and Wpf applications-->
     <NetSdkError Condition="('$(UseWindowsForms)' == 'true') and ('$(PublishTrimmed)' == 'true') and ('$(_SuppressWinFormsTrimError)' != 'true')"
diff --git a/src/Tests/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildASelfContainedApp.cs b/src/Tests/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildASelfContainedApp.cs
index 003f42cf3ea8..268b248a71d3 100644
--- a/src/Tests/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildASelfContainedApp.cs
+++ b/src/Tests/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildASelfContainedApp.cs
@@ -383,6 +383,81 @@ public void It_can_publish_runtime_specific_apps_with_library_dependencies_self_
             publishCommand.Execute(new[] { "-property:SelfContained=true", "-property:_CommandLineDefinedSelfContained=true", $"-property:RuntimeIdentifier={rid}", "-property:_CommandLineDefinedRuntimeIdentifier=true" }).Should().Pass().And.NotHaveStdOutContaining("warning");
         }
 
+        [Theory]
+        [InlineData("net7.0")]
+        [InlineData("net8.0")]
+        public void It_does_or_doesnt_imply_SelfContained_based_on_RuntimeIdentifier_and_TargetFramework(string targetFramework)
+        {
+            var runtimeIdentifier = EnvironmentInfo.GetCompatibleRid(targetFramework);
+            var testAsset = _testAssetsManager
+                .CopyTestAsset("HelloWorld", identifier: targetFramework)
+                .WithSource()
+                .WithProjectChanges(project =>
+                {
+                    var ns = project.Root.Name.Namespace;
+                    var propertyGroup = project.Root.Elements(ns + "PropertyGroup").First();
+                    propertyGroup.Add(new XElement(ns + "RuntimeIdentifier", runtimeIdentifier));
+                });
+
+            var buildCommand = new BuildCommand(testAsset);
+            buildCommand
+                .Execute()
+                .Should()
+                .Pass();
+
+            var outputDirectory = buildCommand.GetOutputDirectory(targetFramework, runtimeIdentifier: runtimeIdentifier);
+            var selfContainedExecutable = $"HelloWorld{Constants.ExeSuffix}";
+            string selfContainedExecutableFullPath = Path.Combine(outputDirectory.FullName, selfContainedExecutable);
+
+            if (targetFramework == "net7.0")
+            {
+                Assert.True(File.Exists(selfContainedExecutableFullPath));
+            }
+            else
+            {
+                Assert.False(File.Exists(selfContainedExecutableFullPath)); // RuntimeIdentifier no longer implies SelfContained for TFM >= 8
+            }
+        }
+
+        [Theory]
+        [InlineData("net7.0", true)]
+        [InlineData("net7.0", false)]
+        [InlineData("net8.0", false)]
+        public void It_does_or_doesnt_warn_based_on_SelfContained_and_TargetFramework_breaking_RID_change(string targetFramework, bool defineSelfContained)
+        {
+            var runtimeIdentifier = EnvironmentInfo.GetCompatibleRid(targetFramework);
+            var testAsset = _testAssetsManager
+                .CopyTestAsset("HelloWorld", identifier: targetFramework + defineSelfContained.ToString())
+                .WithSource()
+                .WithProjectChanges(project =>
+                {
+                    var ns = project.Root.Name.Namespace;
+                    var propertyGroup = project.Root.Elements(ns + "PropertyGroup").First();
+                    propertyGroup.Add(new XElement(ns + "RuntimeIdentifier", runtimeIdentifier));
+                    propertyGroup.Add(new XElement(ns + "SelfContained", defineSelfContained ? "true" : ""));
+                });
+
+            var buildCommand = new BuildCommand(testAsset);
+            var commandResult = buildCommand.Execute();
+
+            if (targetFramework == "net7.0" && !defineSelfContained)
+            {
+                commandResult
+                    .Should()
+                    .Pass()
+                    .And
+                    .HaveStdOutContaining(Strings.RuntimeIdentifierWillNoLongerImplySelfContained);
+            }
+            else
+            {
+                commandResult
+                    .Should()
+                    .Pass()
+                    .And
+                    .NotHaveStdOutContaining(Strings.RuntimeIdentifierWillNoLongerImplySelfContained);
+            }
+        }
+
         [Fact]
         public void It_does_not_build_SelfContained_due_to_PublishSelfContained_being_true()
         {