diff --git a/proposal/sandbox/dotnet/src/etc/testcases/msbuild.xml b/proposal/sandbox/dotnet/src/etc/testcases/msbuild.xml
index 08f92c753..914d17ab0 100644
--- a/proposal/sandbox/dotnet/src/etc/testcases/msbuild.xml
+++ b/proposal/sandbox/dotnet/src/etc/testcases/msbuild.xml
@@ -27,4 +27,31 @@
       <property name="foo" value="bar"/>
     </msbuild>
   </target>
+
+  <target name="nested-file">
+    <property name="foo" value="bar"/>
+    <msbuild 
+      xmlns="antlib:org.apache.tools.ant.taskdefs.optional.dotnet"
+      >
+      <build>
+        <Project DefaultTargets="echo">
+          <Target Name="echo">
+            <Task Name="Echo" Message="foo is ${foo}"/>
+          </Target>
+        </Project>
+      </build>
+    </msbuild>
+  </target>
+
+  <target name="nested-task">
+    <property name="foo" value="bar"/>
+    <msbuild 
+      xmlns="antlib:org.apache.tools.ant.taskdefs.optional.dotnet"
+      >
+      <build>
+        <Task Name="Echo" Message="foo is ${foo}"/>
+      </build>
+    </msbuild>
+  </target>
+
 </project>
\ No newline at end of file
diff --git a/proposal/sandbox/dotnet/src/etc/testcases/nant.xml b/proposal/sandbox/dotnet/src/etc/testcases/nant.xml
index a0f4c775b..f659994f2 100644
--- a/proposal/sandbox/dotnet/src/etc/testcases/nant.xml
+++ b/proposal/sandbox/dotnet/src/etc/testcases/nant.xml
@@ -27,4 +27,30 @@
       <property name="foo" value="bar"/>
     </nant>
   </target>
+
+  <target name="nested-file">
+    <property name="foo" value="bar"/>
+    <nant
+      xmlns="antlib:org.apache.tools.ant.taskdefs.optional.dotnet"
+      >
+      <build>
+        <project basedir="." default="echo">
+          <target name="echo">
+            <echo message="foo is ${foo}"/>
+          </target>
+        </project>
+      </build>
+    </nant>
+  </target>
+
+  <target name="nested-task">
+    <property name="foo" value="bar"/>
+    <nant
+      xmlns="antlib:org.apache.tools.ant.taskdefs.optional.dotnet"
+      >
+      <build>
+        <echo message="foo is ${foo}"/>
+      </build>
+    </nant>
+  </target>
 </project>
\ No newline at end of file
diff --git a/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/AbstractBuildTask.java b/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/AbstractBuildTask.java
index a3fa5d91a..d6ac81008 100644
--- a/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/AbstractBuildTask.java
+++ b/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/AbstractBuildTask.java
@@ -54,9 +54,18 @@
 
 package org.apache.tools.ant.taskdefs.optional.dotnet;
 
+import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.Task;
+import org.apache.tools.ant.util.DOMElementWriter;
+import org.apache.tools.ant.util.FileUtils;
+import org.apache.tools.ant.util.XMLFragment;
+
+import org.w3c.dom.DocumentFragment;
+import org.w3c.dom.Element;
 
 import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -80,6 +89,11 @@ public abstract class AbstractBuildTask extends Task {
      */
     private List properties = new ArrayList(1);
 
+    /**
+     * Nested build file fragment.
+     */
+    private XMLFragment buildSnippet;
+
     /**
      * Empty constructor.
      */
@@ -93,6 +107,18 @@ public abstract class AbstractBuildTask extends Task {
         buildFile = f;
     }
 
+    /**
+     * Adds a build file fragment.
+     */
+    public void addBuild(XMLFragment f) {
+        if (buildSnippet == null) {
+            buildSnippet = f;
+        } else {
+            throw new BuildException("You must not specify more than one "
+                                     + "build element");
+        }
+    }
+
     /**
      * A target.
      */
@@ -180,10 +206,25 @@ public abstract class AbstractBuildTask extends Task {
      */
     protected abstract String[] getPropertyArguments(List properties);
 
+    /**
+     * Turn the DoucmentFragment into a DOM tree suitable as a build
+     * file when serialized.
+     *
+     * <p>Must throw a BuildException if the snippet can not be turned
+     * into a build file.</p>
+     */
+    protected abstract Element makeTree(DocumentFragment f);
+
     /**
      * Perform the build.
      */
     public void execute() {
+        if (buildFile != null && buildSnippet != null) {
+            throw new BuildException("You must not specify the build file"
+                                     + " attribute and a nested build at the"
+                                     + " same time");
+        }
+
         DotNetExecTask exec = new DotNetExecTask();
         exec.setProject(getProject());
         exec.setExecutable(getExecutable());
@@ -196,10 +237,48 @@ public abstract class AbstractBuildTask extends Task {
         for (int i = 0; i < args.length; i++) {
             exec.createArg().setValue(args[i]);
         }
-        args = getBuildfileArguments(buildFile);
+
+        File generatedFile = null;
+        if (buildSnippet != null) {
+            try {
+                generatedFile = getBuildFile();
+            } catch (IOException e) {
+                throw new BuildException(e);
+            }
+            args = getBuildfileArguments(generatedFile);
+        } else {
+            args = getBuildfileArguments(buildFile);
+        }        
+
         for (int i = 0; i < args.length; i++) {
             exec.createArg().setValue(args[i]);
         }
-        exec.execute();
+
+        try {
+            exec.execute();
+        } finally {
+            if (generatedFile != null) {
+                generatedFile.delete();
+            }
+        }
+    }
+
+    private File getBuildFile() throws IOException {
+        File f = null;
+        if (buildSnippet != null) {
+            Element e = makeTree(buildSnippet.getFragment());
+            f = FileUtils.newFileUtils().createTempFile("build", ".xml", null);
+            f.deleteOnExit();
+            FileOutputStream out = null;
+            try {
+                out = new FileOutputStream(f);
+                (new DOMElementWriter()).write(e, out);
+            } finally {
+                if (out != null) {
+                    out.close();
+                }
+            }
+        }
+        return f;
     }
 }
diff --git a/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/MSBuildTask.java b/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/MSBuildTask.java
index f830ec2d1..c87fd1c5e 100644
--- a/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/MSBuildTask.java
+++ b/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/MSBuildTask.java
@@ -59,11 +59,18 @@ import java.util.Iterator;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.w3c.dom.DocumentFragment;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+
 /**
  * Runs a MSBuild build process.
  */
 public class MSBuildTask extends AbstractBuildTask {
 
+    private static final String TARGET = "generated-by-ant";
+
     public MSBuildTask() {
         super();
     }
@@ -119,4 +126,32 @@ public class MSBuildTask extends AbstractBuildTask {
             return new String[0];
         }
     }
+
+    /**
+     * Turn the DocumentFragment into a DOM tree suitable as a build
+     * file when serialized.
+     *
+     * <p>If we have exactly one <Project> child, return that.
+     * Otherwise if we have only <Task> children, wrap them into a
+     * <Target> which in turn gets wrapped into a <Project>.
+     * Otherwise, fail.</p>
+     */
+    protected Element makeTree(DocumentFragment f) {
+        NodeList nl = f.getChildNodes();
+        if (nl.getLength() == 1 
+            && nl.item(0).getNodeType() == Node.ELEMENT_NODE
+            && nl.item(0).getNodeName().equals("Project")) {
+            return (Element) nl.item(0);
+        } else {
+            Element p = f.getOwnerDocument().createElement("Project");
+            p.setAttribute("DefaultTargets", TARGET);
+
+            Element t = f.getOwnerDocument().createElement("Target");
+            t.setAttribute("Name", TARGET);
+
+            p.appendChild(t);
+            t.appendChild(f);
+            return p;
+        }
+    }
 }
diff --git a/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/NAntTask.java b/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/NAntTask.java
index bd228e9fa..95ae7c93a 100644
--- a/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/NAntTask.java
+++ b/proposal/sandbox/dotnet/src/main/org/apache/tools/ant/taskdefs/optional/dotnet/NAntTask.java
@@ -59,6 +59,11 @@ import java.util.Iterator;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.w3c.dom.DocumentFragment;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+
 /**
  * Runs a NAnt build process.
  */
@@ -102,4 +107,25 @@ public class NAntTask extends AbstractBuildTask {
         }
         return (String[]) al.toArray(new String[al.size()]);
     }
+
+    /**
+     * Turn the DocumentFragment into a DOM tree suitable as a build
+     * file when serialized.
+     *
+     * <p>If we have exactly one <project> child, return that.
+     * Otherwise assume that this is a valid build file snippet that
+     * just needs an empty project wrapped around it.</p>
+     */
+    protected Element makeTree(DocumentFragment f) {
+        NodeList nl = f.getChildNodes();
+        if (nl.getLength() == 1 
+            && nl.item(0).getNodeType() == Node.ELEMENT_NODE
+            && nl.item(0).getNodeName().equals("project")) {
+            return (Element) nl.item(0);
+        } else {
+            Element e = f.getOwnerDocument().createElement("project");
+            e.appendChild(f);
+            return e;
+        }
+    }
 }
diff --git a/proposal/sandbox/dotnet/src/testcases/org/apache/tools/ant/taskdefs/optional/dotnet/MSBuildTaskTest.java b/proposal/sandbox/dotnet/src/testcases/org/apache/tools/ant/taskdefs/optional/dotnet/MSBuildTaskTest.java
index 65bc3cb35..efe7797cc 100644
--- a/proposal/sandbox/dotnet/src/testcases/org/apache/tools/ant/taskdefs/optional/dotnet/MSBuildTaskTest.java
+++ b/proposal/sandbox/dotnet/src/testcases/org/apache/tools/ant/taskdefs/optional/dotnet/MSBuildTaskTest.java
@@ -86,4 +86,16 @@ public class MSBuildTaskTest extends BuildFileTest {
             expectLogContaining("echo", "foo is bar");
         }
     }
+
+    public void testNestedFile() throws Exception {
+        if (getProject().getProperty("msbuild.found") != null) {
+            expectLogContaining("nested-file", "foo is bar");
+        }
+    }
+
+    public void testNestedTask() throws Exception {
+        if (getProject().getProperty("msbuild.found") != null) {
+            expectLogContaining("nested-task", "foo is bar");
+        }
+    }
 }
diff --git a/proposal/sandbox/dotnet/src/testcases/org/apache/tools/ant/taskdefs/optional/dotnet/NAntTaskTest.java b/proposal/sandbox/dotnet/src/testcases/org/apache/tools/ant/taskdefs/optional/dotnet/NAntTaskTest.java
index 95d505234..e2f8cd442 100644
--- a/proposal/sandbox/dotnet/src/testcases/org/apache/tools/ant/taskdefs/optional/dotnet/NAntTaskTest.java
+++ b/proposal/sandbox/dotnet/src/testcases/org/apache/tools/ant/taskdefs/optional/dotnet/NAntTaskTest.java
@@ -86,4 +86,16 @@ public class NAntTaskTest extends BuildFileTest {
             expectLogContaining("echo", "foo is bar");
         }
     }
+
+    public void testNestedFile() throws Exception {
+        if (getProject().getProperty("nant.found") != null) {
+            expectLogContaining("nested-file", "foo is bar");
+        }
+    }
+
+    public void testNestedTask() throws Exception {
+        if (getProject().getProperty("nant.found") != null) {
+            expectLogContaining("nested-task", "foo is bar");
+        }
+    }
 }