diff --git a/README.md b/README.md
index 8c0f400..0749f8c 100644
--- a/README.md
+++ b/README.md
@@ -84,6 +84,21 @@ and multi-terminal history support is enabled.
 The vi mode line editor is enabled. [zsh-vim-mode][vim-mode] was a reasonable
 starting point but was replaced as it uses some strange defaults.
 
+#### Cursor Shape
+
+In order to easily ascertain which vi mode the line editor is currently using
+escape sequences are sent to the terminal emulator on certain events to change
+the current shape of the cursor. Two cursor shapes are used; block for `vicmd`
+mode; a vertical line for `viins` mode. Additional escape sequences are used
+when [tmux][tmux] is detected to ensure the terminal emulator receives the
+appropriate sequence. [iTerm2][iterm2] and VTE compatible terminal emulators are
+supported.
+
+Three hooks are registered with the line editor; `zle-keymap-select` changes the
+cursor shape then the mode is changed; `zle-line-init` changes the shape
+starting editing a new command; and `zle-line-finish` resets the cursor shape
+when the line edit is complete.
+
 #### `vicmd` Mode
 
 Undo and repo and enabled using `u` and `U`. Showing help for the command under
@@ -127,4 +142,6 @@ Various aliases are defined at the end of [zshrc](zshrc) for convenience.
 [syntax]: https://github.com/zsh-users/zsh-syntax-highlighting
 [search]: https://github.com/zsh-users/zsh-history-substring-search
 [vim-mode]: https://github.com/sharat87/zsh-vim-mode
+[tmux]: https://tmux.github.io
+[iterm2]: https://www.iterm2.com
 [vim]: http://www.vim.org/
diff --git a/zshrc b/zshrc
index 8701ab7..9eeab79 100644
--- a/zshrc
+++ b/zshrc
@@ -66,6 +66,42 @@ autoload -U edit-command-line
 zle -N edit-command-line
 bindkey -M vicmd '^V' edit-command-line
 
+# Enable changing cursor shape based on vi mode
+if [ "$TMUX" != "" ]; then
+  tmux_before="\EPtmux;\E"
+  tmux_after="\E\\"
+fi
+if [ "$ITERM_SESSION_ID" != "" ]; then
+  # iterm2 cursor shape escape sequences
+  cursor_block="$tmux_before\E]50;CursorShape=0\C-G$tmux_after"
+  cursor_line="$tmux_before\E]50;CursorShape=1\C-G$tmux_after"
+else
+  # VTE compatible cursor shape escape sequences
+  cursor_block="$tmux_before\E[2 q$tmux_after"
+  cursor_line="$tmux_before\E[6 q$tmux_after"
+fi
+unset tmux_before tmux_after
+
+if [[ ! -z "$cursor_block" && ! -z "$cursor_line" ]]; then
+  # Change cursor shape when vi mode changes
+  function zle-keymap-select zle-line-init {
+    case $KEYMAP in
+      vicmd)      print -n -- "$cursor_block" ;;
+      viins|main) print -n -- "$cursor_line" ;;
+    esac
+    zle reset-prompt
+    zle -R
+  }
+
+  # Change cursor shape when line editing is finished
+  function zle-line-finish { print -n -- "$cursor_block" }
+
+  # Register cursor shape hooks
+  zle -N zle-keymap-select
+  zle -N zle-line-init
+  zle -N zle-line-finish
+fi
+
 # Remove duplicates from environment variables
 typeset -U PATH
 typeset -U MANPATH