diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -3139,6 +3139,7 @@
     'PhabricatorDivinerApplication' => 'applications/diviner/application/PhabricatorDivinerApplication.php',
     'PhabricatorDocumentEngine' => 'applications/files/document/PhabricatorDocumentEngine.php',
     'PhabricatorDocumentEngineBlock' => 'applications/files/diff/PhabricatorDocumentEngineBlock.php',
+    'PhabricatorDocumentEngineBlockDiff' => 'applications/files/diff/PhabricatorDocumentEngineBlockDiff.php',
     'PhabricatorDocumentEngineBlocks' => 'applications/files/diff/PhabricatorDocumentEngineBlocks.php',
     'PhabricatorDocumentRef' => 'applications/files/document/PhabricatorDocumentRef.php',
     'PhabricatorDocumentRenderingEngine' => 'applications/files/document/render/PhabricatorDocumentRenderingEngine.php',
@@ -9478,6 +9479,7 @@
     'PhabricatorDivinerApplication' => 'PhabricatorApplication',
     'PhabricatorDocumentEngine' => 'Phobject',
     'PhabricatorDocumentEngineBlock' => 'Phobject',
+    'PhabricatorDocumentEngineBlockDiff' => 'Phobject',
     'PhabricatorDocumentEngineBlocks' => 'Phobject',
     'PhabricatorDocumentRef' => 'Phobject',
     'PhabricatorDocumentRenderingEngine' => 'Phobject',
diff --git a/src/applications/differential/parser/DifferentialChangesetParser.php b/src/applications/differential/parser/DifferentialChangesetParser.php
--- a/src/applications/differential/parser/DifferentialChangesetParser.php
+++ b/src/applications/differential/parser/DifferentialChangesetParser.php
@@ -868,7 +868,15 @@
       ->setHighlightingDisabled($this->highlightingDisabled)
       ->setDepthOnlyLines($this->getDepthOnlyLines());
 
-    $engine_blocks = $this->newDocumentEngineBlocks();
+    list($engine, $old_ref, $new_ref) = $this->newDocumentEngine();
+    if ($engine) {
+      $engine_blocks = $engine->newEngineBlocks(
+        $old_ref,
+        $new_ref);
+    } else {
+      $engine_blocks = null;
+    }
+
     $has_document_engine = ($engine_blocks !== null);
 
     $shield = null;
@@ -1043,7 +1051,9 @@
         $vs = $id;
       }
 
-      $renderer->setDocumentEngineBlocks($engine_blocks);
+      $renderer
+        ->setDocumentEngine($engine)
+        ->setDocumentEngineBlocks($engine_blocks);
 
       return $renderer->renderDocumentEngineBlocks(
         $engine_blocks,
@@ -1657,7 +1667,7 @@
     return $prefix.$line;
   }
 
-  private function newDocumentEngineBlocks() {
+  private function newDocumentEngine() {
     $changeset = $this->changeset;
     $viewer = $this->getViewer();
 
@@ -1728,7 +1738,8 @@
     }
 
     if ($document_engine) {
-      return $document_engine->newEngineBlocks(
+      return array(
+        $document_engine,
         $old_ref,
         $new_ref);
     }
diff --git a/src/applications/differential/render/DifferentialChangesetOneUpRenderer.php b/src/applications/differential/render/DifferentialChangesetOneUpRenderer.php
--- a/src/applications/differential/render/DifferentialChangesetOneUpRenderer.php
+++ b/src/applications/differential/render/DifferentialChangesetOneUpRenderer.php
@@ -242,7 +242,7 @@
         'type' => 'old-file',
         'htype' => '',
         'line' => $block->getBlockKey(),
-        'render' => $block->newContentView(),
+        'render' => $block->getContent(),
       );
     }
 
diff --git a/src/applications/differential/render/DifferentialChangesetRenderer.php b/src/applications/differential/render/DifferentialChangesetRenderer.php
--- a/src/applications/differential/render/DifferentialChangesetRenderer.php
+++ b/src/applications/differential/render/DifferentialChangesetRenderer.php
@@ -35,6 +35,8 @@
   private $highlightingDisabled;
   private $scopeEngine = false;
   private $depthOnlyLines;
+
+  private $documentEngine;
   private $documentEngineBlocks;
 
   private $oldFile = false;
@@ -240,6 +242,15 @@
     return $this->oldChangesetID;
   }
 
+  public function setDocumentEngine(PhabricatorDocumentEngine $engine) {
+    $this->documentEngine = $engine;
+    return $this;
+  }
+
+  public function getDocumentEngine() {
+    return $this->documentEngine;
+  }
+
   public function setDocumentEngineBlocks(
     PhabricatorDocumentEngineBlocks $blocks) {
     $this->documentEngineBlocks = $blocks;
diff --git a/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php b/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php
--- a/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php
+++ b/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php
@@ -369,6 +369,15 @@
     $old_changeset_key,
     $new_changeset_key) {
 
+    $engine = $this->getDocumentEngine();
+
+    $old_ref = null;
+    $new_ref = null;
+    $refs = $block_list->getDocumentRefs();
+    if ($refs) {
+      list($old_ref, $new_ref) = $refs;
+    }
+
     $old_comments = $this->getOldComments();
     $new_comments = $this->getNewComments();
 
@@ -392,41 +401,16 @@
 
       if ($old) {
         $old_key = $old->getBlockKey();
-
-        $old_classes = $old->getClasses();
-
-        if ($old->getDifferenceType() === '-') {
-          $old_classes[] = 'old';
-          $old_classes[] = 'old-full';
-        }
-
-        $old_classes[] = 'diff-flush';
-
-        $old_classes = implode(' ', $old_classes);
-
         $is_visible = $old->getIsVisible();
       } else {
         $old_key = null;
-        $old_classes = null;
       }
 
       if ($new) {
         $new_key = $new->getBlockKey();
-        $new_classes = $new->getClasses();
-
-        if ($new->getDifferenceType() === '+') {
-          $new_classes[] = 'new';
-          $new_classes[] = 'new-full';
-        }
-
-        $new_classes[] = 'diff-flush';
-
-        $new_classes = implode(' ', $new_classes);
-
         $is_visible = $new->getIsVisible();
       } else {
         $new_key = null;
-        $new_classes = null;
       }
 
       if (!$is_visible) {
@@ -454,24 +438,54 @@
       }
 
       if ($is_rem && $is_add) {
-        list($old_content, $new_content) = array(
-          $old->newContentView(),
-          $new->newContentView(),
-        );
+        $block_diff = $engine->newBlockDiffViews(
+          $old_ref,
+          $old,
+          $new_ref,
+          $new);
+
+        $old_content = $block_diff->getOldContent();
+        $new_content = $block_diff->getNewContent();
+
+        $old_classes = $block_diff->getOldClasses();
+        $new_classes = $block_diff->getNewClasses();
       } else {
+        $old_classes = array();
+        $new_classes = array();
+
         if ($old) {
-          $old_content = $old->newContentView();
+          $old_content = $engine->newBlockContentView(
+            $old_ref,
+            $old);
+
+          if ($is_rem) {
+            $old_classes[] = 'old';
+            $old_classes[] = 'old-full';
+          }
         } else {
           $old_content = null;
         }
 
         if ($new) {
-          $new_content = $new->newContentView();
+          $new_content = $engine->newBlockContentView(
+            $new_ref,
+            $new);
+
+          if ($is_add) {
+            $new_classes[] = 'new';
+            $new_classes[] = 'new-full';
+          }
         } else {
           $new_content = null;
         }
       }
 
+      $old_classes[] = 'diff-flush';
+      $old_classes = implode(' ', $old_classes);
+
+      $new_classes[] = 'diff-flush';
+      $new_classes = implode(' ', $new_classes);
+
       $old_inline_rows = array();
       if ($old_key !== null) {
         $old_inlines = idx($old_comments, $old_key, array());
diff --git a/src/applications/files/diff/PhabricatorDocumentEngineBlock.php b/src/applications/files/diff/PhabricatorDocumentEngineBlock.php
--- a/src/applications/files/diff/PhabricatorDocumentEngineBlock.php
+++ b/src/applications/files/diff/PhabricatorDocumentEngineBlock.php
@@ -5,7 +5,6 @@
 
   private $blockKey;
   private $content;
-  private $classes = array();
   private $differenceHash;
   private $differenceType;
   private $isVisible;
@@ -19,10 +18,6 @@
     return $this->content;
   }
 
-  public function newContentView() {
-    return $this->getContent();
-  }
-
   public function setBlockKey($block_key) {
     $this->blockKey = $block_key;
     return $this;
@@ -32,15 +27,6 @@
     return $this->blockKey;
   }
 
-  public function addClass($class) {
-    $this->classes[] = $class;
-    return $this;
-  }
-
-  public function getClasses() {
-    return $this->classes;
-  }
-
   public function setDifferenceHash($difference_hash) {
     $this->differenceHash = $difference_hash;
     return $this;
diff --git a/src/applications/files/diff/PhabricatorDocumentEngineBlockDiff.php b/src/applications/files/diff/PhabricatorDocumentEngineBlockDiff.php
new file mode 100644
--- /dev/null
+++ b/src/applications/files/diff/PhabricatorDocumentEngineBlockDiff.php
@@ -0,0 +1,47 @@
+<?php
+
+final class PhabricatorDocumentEngineBlockDiff
+  extends Phobject {
+
+  private $oldContent;
+  private $newContent;
+  private $oldClasses = array();
+  private $newClasses = array();
+
+  public function setOldContent($old_content) {
+    $this->oldContent = $old_content;
+    return $this;
+  }
+
+  public function getOldContent() {
+    return $this->oldContent;
+  }
+
+  public function setNewContent($new_content) {
+    $this->newContent = $new_content;
+    return $this;
+  }
+
+  public function getNewContent() {
+    return $this->newContent;
+  }
+
+  public function addOldClass($class) {
+    $this->oldClasses[] = $class;
+    return $this;
+  }
+
+  public function getOldClasses() {
+    return $this->oldClasses;
+  }
+
+  public function addNewClass($class) {
+    $this->newClasses[] = $class;
+    return $this;
+  }
+
+  public function getNewClasses() {
+    return $this->newClasses;
+  }
+
+}
diff --git a/src/applications/files/diff/PhabricatorDocumentEngineBlocks.php b/src/applications/files/diff/PhabricatorDocumentEngineBlocks.php
--- a/src/applications/files/diff/PhabricatorDocumentEngineBlocks.php
+++ b/src/applications/files/diff/PhabricatorDocumentEngineBlocks.php
@@ -26,6 +26,10 @@
     return $this;
   }
 
+  public function getDocumentRefs() {
+    return ipull($this->lists, 'ref');
+  }
+
   public function newTwoUpLayout() {
     $rows = array();
     $lists = $this->lists;
diff --git a/src/applications/files/document/PhabricatorDocumentEngine.php b/src/applications/files/document/PhabricatorDocumentEngine.php
--- a/src/applications/files/document/PhabricatorDocumentEngine.php
+++ b/src/applications/files/document/PhabricatorDocumentEngine.php
@@ -37,6 +37,30 @@
     return false;
   }
 
+  public function newBlockDiffViews(
+    PhabricatorDocumentRef $uref,
+    PhabricatorDocumentEngineBlock $ublock,
+    PhabricatorDocumentRef $vref,
+    PhabricatorDocumentEngineBlock $vblock) {
+
+    $u_content = $this->newBlockContentView($uref, $ublock);
+    $v_content = $this->newBlockContentView($vref, $vblock);
+
+    return id(new PhabricatorDocumentEngineBlockDiff())
+      ->setOldContent($u_content)
+      ->addOldClass('old')
+      ->addOldClass('old-full')
+      ->setNewContent($v_content)
+      ->addNewClass('new')
+      ->addNewClass('new-full');
+  }
+
+  public function newBlockContentView(
+    PhabricatorDocumentRef $ref,
+    PhabricatorDocumentEngineBlock $block) {
+    return $block->getContent();
+  }
+
   public function newEngineBlocks(
     PhabricatorDocumentRef $uref,
     PhabricatorDocumentRef $vref) {
diff --git a/src/applications/files/document/PhabricatorImageDocumentEngine.php b/src/applications/files/document/PhabricatorImageDocumentEngine.php
--- a/src/applications/files/document/PhabricatorImageDocumentEngine.php
+++ b/src/applications/files/document/PhabricatorImageDocumentEngine.php
@@ -39,6 +39,23 @@
       ->addBlockList($vref, $v_blocks);
   }
 
+  public function newBlockDiffViews(
+    PhabricatorDocumentRef $uref,
+    PhabricatorDocumentEngineBlock $ublock,
+    PhabricatorDocumentRef $vref,
+    PhabricatorDocumentEngineBlock $vblock) {
+
+    $u_content = $this->newBlockContentView($uref, $ublock);
+    $v_content = $this->newBlockContentView($vref, $vblock);
+
+    return id(new PhabricatorDocumentEngineBlockDiff())
+      ->setOldContent($u_content)
+      ->addOldClass('diff-image-cell')
+      ->setNewContent($v_content)
+      ->addNewClass('diff-image-cell');
+  }
+
+
   private function newDiffBlocks(PhabricatorDocumentRef $ref) {
     $blocks = array();
 
@@ -59,7 +76,6 @@
 
     $blocks[] = id(new PhabricatorDocumentEngineBlock())
       ->setBlockKey('1')
-      ->addClass('diff-image-cell')
       ->setDifferenceHash($hash)
       ->setContent($image_view);
 
diff --git a/src/applications/files/document/PhabricatorJupyterDocumentEngine.php b/src/applications/files/document/PhabricatorJupyterDocumentEngine.php
--- a/src/applications/files/document/PhabricatorJupyterDocumentEngine.php
+++ b/src/applications/files/document/PhabricatorJupyterDocumentEngine.php
@@ -60,31 +60,135 @@
     return $blocks;
   }
 
-  private function newDiffBlocks(PhabricatorDocumentRef $ref) {
+  public function newBlockDiffViews(
+    PhabricatorDocumentRef $uref,
+    PhabricatorDocumentEngineBlock $ublock,
+    PhabricatorDocumentRef $vref,
+    PhabricatorDocumentEngineBlock $vblock) {
+
+    $ucell = $ublock->getContent();
+    $vcell = $vblock->getContent();
+
+    $utype = idx($ucell, 'cell_type');
+    $vtype = idx($vcell, 'cell_type');
+
+    if ($utype === $vtype) {
+      switch ($utype) {
+        case 'markdown':
+          $usource = idx($ucell, 'source');
+          $usource = implode('', $usource);
+
+          $vsource = idx($vcell, 'source');
+          $vsource = implode('', $vsource);
+
+          $diff = id(new PhutilProseDifferenceEngine())
+            ->getDiff($usource, $vsource);
+
+          $u_content = $this->newProseDiffCell($diff, array('=', '-'));
+          $v_content = $this->newProseDiffCell($diff, array('=', '+'));
+
+          $u_content = $this->newJupyterCell(null, $u_content, null);
+          $v_content = $this->newJupyterCell(null, $v_content, null);
+
+          $u_content = $this->newCellContainer($u_content);
+          $v_content = $this->newCellContainer($v_content);
+
+          return id(new PhabricatorDocumentEngineBlockDiff())
+            ->setOldContent($u_content)
+            ->addOldClass('old')
+            ->setNewContent($v_content)
+            ->addNewClass('new');
+      }
+    }
+
+    return parent::newBlockDiffViews($uref, $ublock, $vref, $vblock);
+  }
+
+  public function newBlockContentView(
+    PhabricatorDocumentRef $ref,
+    PhabricatorDocumentEngineBlock $block) {
+
     $viewer = $this->getViewer();
-    $content = $ref->loadData();
+    $cell = $block->getContent();
 
-    $cells = $this->newCells($content, true);
+    $cell_content = $this->renderJupyterCell($viewer, $cell);
 
-    $idx = 1;
-    $blocks = array();
-    foreach ($cells as $cell) {
-      $cell_content = $this->renderJupyterCell($viewer, $cell);
+    return $this->newCellContainer($cell_content);
+  }
 
-      $notebook_table = phutil_tag(
-        'table',
-        array(
-          'class' => 'jupyter-notebook',
-        ),
-        $cell_content);
+  private function newCellContainer($cell_content) {
+    $notebook_table = phutil_tag(
+      'table',
+      array(
+        'class' => 'jupyter-notebook',
+      ),
+      $cell_content);
+
+    $container = phutil_tag(
+      'div',
+      array(
+        'class' => 'document-engine-jupyter document-engine-diff',
+      ),
+      $notebook_table);
 
-      $container = phutil_tag(
+    return $container;
+  }
+
+  private function newProseDiffCell(PhutilProseDiff $diff, array $mask) {
+    $mask = array_fuse($mask);
+
+    $result = array();
+    foreach ($diff->getParts() as $part) {
+      $type = $part['type'];
+      $text = $part['text'];
+
+      if (!isset($mask[$type])) {
+        continue;
+      }
+
+      switch ($type) {
+        case '-':
+          $result[] = phutil_tag(
+            'span',
+            array(
+              'class' => 'bright',
+            ),
+            $text);
+          break;
+        case '+':
+          $result[] = phutil_tag(
+            'span',
+            array(
+              'class' => 'bright',
+            ),
+            $text);
+          break;
+        case '=':
+          $result[] = $text;
+          break;
+      }
+    }
+
+    return array(
+      null,
+      phutil_tag(
         'div',
         array(
-          'class' => 'document-engine-jupyter document-engine-diff',
+          'class' => 'jupyter-cell-markdown',
         ),
-        $notebook_table);
+        $result),
+    );
+  }
 
+  private function newDiffBlocks(PhabricatorDocumentRef $ref) {
+    $viewer = $this->getViewer();
+    $content = $ref->loadData();
+
+    $cells = $this->newCells($content, true);
+
+    $idx = 1;
+    $blocks = array();
+    foreach ($cells as $cell) {
       // When the cell is a source code line, we can hash just the raw
       // input rather than all the cell metadata.
 
@@ -92,6 +196,9 @@
         case 'code/line':
           $hash_input = $cell['raw'];
           break;
+        case 'markdown':
+          $hash_input = implode('', $cell['source']);
+          break;
         default:
           $hash_input = serialize($cell);
           break;
@@ -104,7 +211,7 @@
       $blocks[] = id(new PhabricatorDocumentEngineBlock())
         ->setBlockKey($idx)
         ->setDifferenceHash($hash)
-        ->setContent($container);
+        ->setContent($cell);
 
       $idx++;
     }
@@ -204,6 +311,26 @@
     foreach ($cells as $cell) {
       $cell_type = idx($cell, 'cell_type');
 
+      if ($cell_type === 'markdown') {
+        $source = $cell['source'];
+        $source = implode('', $source);
+
+        // Attempt to split contiguous blocks of markdown into smaller
+        // pieces.
+
+        $chunks = preg_split(
+          '/\n\n+/',
+          $source);
+
+        foreach ($chunks as $chunk) {
+          $result = $cell;
+          $result['source'] = array($chunk);
+          $results[] = $result;
+        }
+
+        continue;
+      }
+
       if ($cell_type !== 'code') {
         $results[] = $cell;
         continue;
@@ -261,13 +388,6 @@
 
     list($label, $content) = $this->renderJupyterCellContent($viewer, $cell);
 
-    $label_cell = phutil_tag(
-      'td',
-      array(
-        'class' => 'jupyter-label',
-      ),
-      $label);
-
     $classes = null;
     switch (idx($cell, 'cell_type')) {
       case 'code/line':
@@ -275,6 +395,20 @@
         break;
     }
 
+    return $this->newJupyterCell(
+      $label,
+      $content,
+      $classes);
+  }
+
+  private function newJupyterCell($label, $content, $classes) {
+    $label_cell = phutil_tag(
+      'td',
+      array(
+        'class' => 'jupyter-label',
+      ),
+      $label);
+
     $content_cell = phutil_tag(
       'td',
       array(