diff --git a/TODO b/TODO
index a5aedf6..4649b83 100644
--- a/TODO
+++ b/TODO
@@ -2,7 +2,6 @@ Todo:
 - Keyboard shortcuts for resolving differences.
 - How to handle tabs?
 - Colourise file name.
-- Bulk indent/dedent.
 - Search.
 - Search and replace.
 - Large pastes.
@@ -31,6 +30,7 @@ Done:
 - tab key should align code.
 - Right align the left editor.
 - Overwrite mode.
+- Bulk indent/dedent.
 
 
 Shelved:
diff --git a/diff_edit/editor.py b/diff_edit/editor.py
index 5f6934a..efab6dc 100755
--- a/diff_edit/editor.py
+++ b/diff_edit/editor.py
@@ -16,7 +16,7 @@ import pygments.lexers
 import pygments.styles
 import termstr
 
-   
+
 @functools.lru_cache(maxsize=100)
 def highlight_str(line, bg_color, transparency=0.6):
     def blend_style(style):
@@ -181,6 +181,7 @@ def add_highlights(self, appearance):
 
 class Editor:
 
+    TAB_SIZE = 4
     THEMES = [pygments.styles.get_style_by_name(style)
               for style in ["monokai", "fruity", "native"]] + [None]
 
@@ -538,6 +539,50 @@ class Editor:
     def toggle_overwrite(self):
         self.is_overwriting = not self.is_overwriting
 
+    def _work_lines(self):
+        if self.mark is None:
+            return [self.cursor_y]
+        else:
+            (start_x, start_y), (end_x, end_y) = self.get_selection_interval()
+            return range(start_y + (start_x > 0), end_y + 1 - (end_x == 0))
+
+    def indent(self):
+        indent_ = " " * Editor.TAB_SIZE
+        for line_num in self._work_lines():
+            if self.text_widget[line_num].strip() == "":
+                self.text_widget[line_num] = ""
+                continue
+            self.text_widget[line_num] = indent_ + self.text_widget[line_num]
+            if self.cursor_y == line_num:
+                self.cursor_x += Editor.TAB_SIZE
+
+    def dedent(self):
+        indent_ = " " * Editor.TAB_SIZE
+        line_nums = self._work_lines()
+        if not all(self.text_widget[line_num].startswith(indent_)
+                   or self.text_widget[line_num].strip() == "" for line_num in line_nums):
+            self.ring_bell()
+            return
+        for line_num in line_nums:
+            if self.cursor_y == line_num:
+                self.cursor_x = max(self.cursor_x - Editor.TAB_SIZE, 0)
+            if self.text_widget[line_num].strip() == "":
+                self.text_widget[line_num] = ""
+                continue
+            self.text_widget[line_num] = self.text_widget[line_num][Editor.TAB_SIZE:]
+
+    def greater_than_key(self):
+        if self.previous_term_code == terminal.CTRL_C:
+            self.indent()
+        else:
+            self.insert_text(">", is_overwriting=self.is_overwriting)
+
+    def less_than_key(self):
+        if self.previous_term_code == terminal.CTRL_C:
+            self.dedent()
+        else:
+            self.insert_text("<", is_overwriting=self.is_overwriting)
+
     def abort_command(self):
         self.mark = None
         self.ring_bell()
@@ -621,7 +666,6 @@ class Editor:
 
     def appearance_for(self, dimensions):
         width, height = dimensions
-        text_width = self.text_widget.max_line_length
         is_changed = self.text_widget.actual_text != self.original_text
         header = self.get_header(self.path, width, self.cursor_x, self.cursor_y, is_changed)
         self.last_width = width
@@ -650,7 +694,7 @@ class Editor:
         terminal.ALT_c: cycle_syntax_highlighting, terminal.CTRL_X: prefix, terminal.ESC: quit,
         terminal.CTRL_C: ctrl_c, terminal.CTRL_K: delete_line, terminal.TAB: tab_align,
         terminal.CTRL_UNDERSCORE: undo, terminal.CTRL_Z: undo, terminal.CTRL_G: abort_command,
-        terminal.INSERT: toggle_overwrite}
+        terminal.INSERT: toggle_overwrite, ">": greater_than_key, "<": less_than_key}
 
 
 def main():
diff --git a/tests/editor_test.py b/tests/editor_test.py
index 4987c53..871ad6b 100755
--- a/tests/editor_test.py
+++ b/tests/editor_test.py
@@ -1,7 +1,6 @@
 #!/usr/bin/env python3
 
 
-import contextlib
 import unittest
 
 import diff_edit.editor as editor
@@ -90,6 +89,47 @@ class EditorTestCase(unittest.TestCase):
         self.editor.insert_text("ef", is_overwriting=True)
         self._assert_editor("aef", (3, 0))
 
+    def test_indent(self):
+        # no selection
+        self._set_editor("ab", (1, 0))
+        self._assert_change(self.editor.indent, "    ab", (5, 0))
+        self._set_editor("   ", (1, 0))
+        self._assert_change(self.editor.indent, "", (0, 0))
+        # on selection
+        self._set_editor("a\nb\nc", (0, 0))
+        self.editor.set_mark()
+        self.editor.cursor_down()
+        self._assert_change(self.editor.indent, "    a\nb\nc", (0, 1))
+        self.assertIsNotNone(self.editor.mark)
+        self._set_editor("a\nb\nc", (1, 0))
+        self.editor.set_mark()
+        self.editor.cursor_left()
+        self.editor.cursor_down()
+        self.editor.cursor_down()
+        self._assert_change(self.editor.indent, "a\n    b\nc", (0, 2))
+        self._set_editor("a\nb\nc", (0, 1))
+        self.editor.set_mark()
+        self.editor.cursor_down()
+        self.editor.cursor_right()
+        self._assert_change(self.editor.indent, "a\n    b\n    c", (5, 2))
+
+    def test_dedent(self):
+        # no selection
+        self._set_editor("    ab", (2, 0))
+        self._assert_change(self.editor.dedent, "ab", (0, 0))
+        self._set_editor("    ab", (5, 0))
+        self._assert_change(self.editor.dedent, "ab", (1, 0))
+        self._set_editor("   ab", (0, 0))
+        self._assert_change(self.editor.dedent, "   ab", (0, 0))
+        self._set_editor("   ", (1, 0))
+        self._assert_change(self.editor.dedent, "", (0, 0))
+        # on selection
+        self._set_editor("    a\n  \n    b", (0, 0))
+        self.editor.set_mark()
+        self.editor.cursor_down()
+        self.editor.cursor_down()
+        self._assert_change(self.editor.dedent, "a\n\n    b", (0, 2))
+
     def test_enter(self):
         self._set_editor("ab", (1, 0))
         self.editor.enter()