diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/CommitData.java b/gitiles-servlet/src/main/java/com/google/gitiles/CommitData.java
index 3048aa8..76f5273 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/CommitData.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/CommitData.java
@@ -66,6 +66,7 @@
     LOG_URL,
     MESSAGE,
     PARENTS,
+    PARENT_BLAME_URL,
     SHA,
     SHORT_MESSAGE,
     TAGS,
diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/CommitSoyData.java b/gitiles-servlet/src/main/java/com/google/gitiles/CommitSoyData.java
index 3e77d8d..8127d6d 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/CommitSoyData.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/CommitSoyData.java
@@ -52,6 +52,9 @@
       Field.COMMITTER, Field.SHA, Field.TREE, Field.TREE_URL, Field.PARENTS, Field.MESSAGE,
       Field.LOG_URL, Field.ARCHIVE_URL, Field.ARCHIVE_TYPE);
 
+  private static final ImmutableSet<Field> NESTED_FIELDS = Sets.immutableEnumSet(
+      Field.PARENT_BLAME_URL);
+
   private Linkifier linkifier;
   private RevWalk walk;
   private ArchiveFormat archiveFormat;
@@ -111,7 +114,7 @@
       data.put("treeUrl", cd.treeUrl);
     }
     if (cd.parents != null) {
-      data.put("parents", toSoyData(view, cd.parents));
+      data.put("parents", toSoyData(view, fs, cd.parents));
     }
     if (cd.shortMessage != null) {
       data.put("shortMessage", cd.shortMessage);
@@ -132,7 +135,8 @@
     if (cd.diffEntries != null) {
       data.put("diffTree", toSoyData(view, cd.diffEntries));
     }
-    checkState(fs.size() == data.size(), "bad commit data fields: %s != %s", fs, data.keySet());
+    checkState(Sets.difference(fs, NESTED_FIELDS).size() == data.size(),
+        "bad commit data fields: %s != %s", fs, data.keySet());
     return ImmutableMap.copyOf(data);
   }
 
@@ -151,7 +155,8 @@
         "relativeTime", RelativeDateFormatter.format(ident.getWhen()));
   }
 
-  private List<Map<String, String>> toSoyData(GitilesView view, List<RevCommit> parents) {
+  private List<Map<String, String>> toSoyData(GitilesView view, Set<Field> fs,
+      List<RevCommit> parents) {
     List<Map<String, String>> result = Lists.newArrayListWithCapacity(parents.size());
     int i = 1;
     // TODO(dborowitz): Render something slightly different when we're actively
@@ -167,13 +172,21 @@
       } else {
         parentName = view.getRevision().getName() + "^" + (i++);
       }
-      result.add(ImmutableMap.of(
-          "sha", name,
-          "url", GitilesView.revision()
-              .copyFrom(view)
-              .setRevision(parentName, parent)
-              .toUrl(),
-          "diffUrl", diff.setOldRevision(parentName, parent).toUrl()));
+      Map<String, String> e = Maps.newHashMapWithExpectedSize(4);
+      e.put("sha", name);
+      e.put("url", GitilesView.revision()
+          .copyFrom(view)
+          .setRevision(parentName, parent)
+          .toUrl());
+      e.put("diffUrl", diff.setOldRevision(parentName, parent).toUrl());
+      if (fs.contains(Field.PARENT_BLAME_URL)) {
+        // Assumes caller has ensured path is a file.
+        e.put("blameUrl", GitilesView.blame()
+            .copyFrom(view)
+            .setRevision(Revision.peeled(parentName, parent))
+            .toUrl());
+      }
+      result.add(e);
     }
     return result;
   }
diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java b/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java
index bf90bf7..ebe89e2 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java
@@ -18,11 +18,13 @@
 import static javax.servlet.http.HttpServletResponse.SC_NOT_FOUND;
 
 import com.google.common.base.Charsets;
+import com.google.gitiles.CommitData.Field;
 
 import org.eclipse.jgit.diff.DiffFormatter;
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.http.server.ServletUtils;
+import org.eclipse.jgit.lib.FileMode;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
@@ -30,6 +32,7 @@
 import org.eclipse.jgit.treewalk.AbstractTreeIterator;
 import org.eclipse.jgit.treewalk.CanonicalTreeParser;
 import org.eclipse.jgit.treewalk.EmptyTreeIterator;
+import org.eclipse.jgit.treewalk.TreeWalk;
 import org.eclipse.jgit.treewalk.filter.PathFilter;
 import org.eclipse.jgit.util.GitDateFormatter;
 import org.eclipse.jgit.util.GitDateFormatter.Format;
@@ -38,6 +41,7 @@
 import java.io.OutputStream;
 import java.util.Arrays;
 import java.util.Map;
+import java.util.Set;
 
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
@@ -62,19 +66,17 @@
 
     RevWalk walk = new RevWalk(repo);
     try {
-      boolean showCommit;
+      boolean showCommit, isFile;
       AbstractTreeIterator oldTree;
       AbstractTreeIterator newTree;
       try {
         // If we are viewing the diff between a commit and one of its parents,
         // include the commit detail in the rendered page.
         showCommit = isParentOf(walk, view.getOldRevision(), view.getRevision());
+        isFile = showCommit ? isFile(walk, view) : false;
         oldTree = getTreeIterator(walk, view.getOldRevision().getId());
         newTree = getTreeIterator(walk, view.getRevision().getId());
-      } catch (MissingObjectException e) {
-        res.setStatus(SC_NOT_FOUND);
-        return;
-      } catch (IncorrectObjectTypeException e) {
+      } catch (MissingObjectException | IncorrectObjectTypeException e) {
         res.setStatus(SC_NOT_FOUND);
         return;
       }
@@ -82,11 +84,15 @@
       Map<String, Object> data = getData(req);
       data.put("title", "Diff - " + view.getRevisionRange());
       if (showCommit) {
+        Set<Field> fs = CommitSoyData.DEFAULT_FIELDS;
+        if (isFile) {
+          fs = Field.setOf(fs, Field.PARENT_BLAME_URL);
+        }
         GitDateFormatter df = new GitDateFormatter(Format.DEFAULT);
         data.put("commit", new CommitSoyData()
             .setLinkifier(linkifier)
             .setArchiveFormat(getArchiveFormat(getAccess(req)))
-            .toSoyData(req, walk.parseCommit(view.getRevision().getId()), df));
+            .toSoyData(req, walk.parseCommit(view.getRevision().getId()), fs, df));
       }
       if (!data.containsKey("repositoryName") && (view.getRepositoryName() != null)) {
         data.put("repositoryName", view.getRepositoryName());
@@ -124,6 +130,21 @@
     }
   }
 
+  private static boolean isFile(RevWalk walk, GitilesView view) throws IOException {
+    if (view.getPathPart().equals("")) {
+      return false;
+    }
+    TreeWalk tw = TreeWalk.forPath(
+        walk.getObjectReader(),
+        view.getPathPart(),
+        walk.parseTree(view.getRevision().getId()));
+    try {
+      return (tw.getRawMode(0) & FileMode.TYPE_FILE) > 0;
+    } finally {
+      tw.release();
+    }
+  }
+
   private String[] renderAndSplit(Map<String, Object> data) {
     String html = renderer.newRenderer("gitiles.diffDetail")
         .setData(data)
diff --git a/gitiles-servlet/src/main/resources/com/google/gitiles/templates/ObjectDetail.soy b/gitiles-servlet/src/main/resources/com/google/gitiles/templates/ObjectDetail.soy
index c6ca22e..66a0d75 100644
--- a/gitiles-servlet/src/main/resources/com/google/gitiles/templates/ObjectDetail.soy
+++ b/gitiles-servlet/src/main/resources/com/google/gitiles/templates/ObjectDetail.soy
@@ -25,6 +25,7 @@
  *     sha: SHA-1.
  *     url: URL to view the parent commit.
  *     diffUrl: URL to display diffs relative to this parent.
+ *     blameUrl: optional URL to display blame of a file at this parent.
  * @param message list of commit message parts, where each part contains:
  *     text: raw text of the part.
  *     url: optional URL that should be linked to from the part.
@@ -74,6 +75,9 @@
           <a href="{$parent.url}">{$parent.sha}</a>
           <span class="diff-link">
             [<a href="{$parent.diffUrl}">{msg desc="text for the parent diff link"}diff{/msg}</a>]
+            {if isNonnull($parent.blameUrl)}
+              {sp}[<a href="{$parent.blameUrl}">{msg desc="text for the parent blame link"}blame{/msg}</a>]
+            {/if}
           </span>
         </td>
       </tr>