diff --git a/css/app.css b/css/app.css
index 6e2772cdd..8f17d668a 100644
--- a/css/app.css
+++ b/css/app.css
@@ -349,3 +349,45 @@ div.typeahead a.active {
     -webkit-tap-highlight-color:rgba(0,0,0,0);
     -webkit-touch-callout:none;
 }
+
+.tooltip {
+  position: absolute;
+  z-index: 1030;
+  display: block;
+  padding: 5px;
+  font-size: 11px;
+  opacity: 0;
+  filter: alpha(opacity=0);
+  visibility: visible;
+}
+
+.tooltip.in {
+  opacity: 0.8;
+  filter: alpha(opacity=80);
+}
+
+.tooltip-inner {
+  max-width: 200px;
+  padding: 3px 8px;
+  color: #ffffff;
+  text-align: center;
+  text-decoration: none;
+  background-color: #000000;
+  -webkit-border-radius: 4px;
+     -moz-border-radius: 4px;
+          border-radius: 4px;
+}
+.tooltip-arrow {
+  position: absolute;
+  width: 0;
+  height: 0;
+  border-color: transparent;
+  border-style: solid;
+}
+.tooltip.bottom .tooltip-arrow {
+  top: 0;
+  left: 50%;
+  margin-left: -5px;
+  border-bottom-color: #000000;
+  border-width: 0 5px 5px;
+}
diff --git a/index.html b/index.html
index 77fce4dff..ab9e86956 100644
--- a/index.html
+++ b/index.html
@@ -21,6 +21,8 @@
         <script src='js/lib/d3.geo.tile.js'></script>
         <script src='js/lib/d3.size.js'></script>
         <script src='js/lib/d3.keybinding.js'></script>
+        <script src='js/lib/d3-compat.js'></script>
+        <script src='js/lib/bootstrap-tooltip.js'></script>
 
         <script src='js/id/id.js'></script>
         <script src='js/id/util.js'></script>
diff --git a/js/id/id.js b/js/id/id.js
index a58dfafb2..87a6b40f1 100644
--- a/js/id/id.js
+++ b/js/id/id.js
@@ -46,13 +46,17 @@ window.iD = function(container) {
             .attr({ id: 'undo', 'class': 'mini' })
             .property('disabled', true)
             .html('&larr;<small></small>')
-            .on('click', history.undo);
+            .on('click', history.undo)
+            .call(bootstrap.tooltip()
+                .placement('bottom'));
 
         undo_buttons.append('button')
             .attr({ id: 'redo', 'class': 'mini' })
             .property('disabled', true)
             .html('&rarr;<small></small>')
-            .on('click', history.redo);
+            .on('click', history.redo)
+            .call(bootstrap.tooltip()
+                .placement('bottom'));
 
         bar.append('input')
             .attr({ type: 'text', placeholder: 'find a place', id: 'geocode-location' })
@@ -137,13 +141,11 @@ window.iD = function(container) {
 
             bar.select('#undo')
                 .property('disabled', !undo)
-                .select('small')
-                .text(undo);
+                .attr('data-original-title', undo);
 
             bar.select('#redo')
                 .property('disabled', !redo)
-                .select('small')
-                .text(redo);
+                .attr('data-original-title', redo);
         });
 
         window.onresize = function() {
diff --git a/js/lib/bootstrap-tooltip.js b/js/lib/bootstrap-tooltip.js
new file mode 100644
index 000000000..8cdf669d5
--- /dev/null
+++ b/js/lib/bootstrap-tooltip.js
@@ -0,0 +1,166 @@
+(function(exports) {
+
+  var bootstrap = (typeof exports.bootstrap === "object") ?
+    exports.bootstrap :
+    (exports.bootstrap = {});
+
+  bootstrap.tooltip = function() {
+
+    var tooltip = function(selection) {
+        selection.each(setup);
+      },
+      animation = d3.functor(false),
+      html = d3.functor(false),
+      title = function() {
+        var title = this.getAttribute("data-original-title");
+        if (title) {
+          return title;
+        } else {
+          title = this.getAttribute("title");
+          this.removeAttribute("title");
+          this.setAttribute("data-original-title", title);
+        }
+        return title;
+      },
+      over = "mouseenter.tooltip",
+      out = "mouseleave.tooltip",
+      placements = "top left bottom right".split(" "),
+      placement = d3.functor("top");
+
+    tooltip.title = function(_) {
+      if (arguments.length) {
+        title = d3.functor(_);
+        return tooltip;
+      } else {
+        return title;
+      }
+    };
+
+    tooltip.html = function(_) {
+      if (arguments.length) {
+        html = d3.functor(_);
+        return tooltip;
+      } else {
+        return html;
+      }
+    };
+
+    tooltip.placement = function(_) {
+      if (arguments.length) {
+        placement = d3.functor(_);
+        return tooltip;
+      } else {
+        return placement;
+      }
+    };
+
+    tooltip.show = function(selection) {
+      selection.each(show);
+    };
+
+    tooltip.hide = function(selection) {
+      selection.each(hide);
+    };
+
+    tooltip.toggle = function(selection) {
+      selection.each(toggle);
+    };
+
+    tooltip.destroy = function(selection) {
+      selection
+        .on(over, null)
+        .on(out, null)
+        .attr("title", function() {
+          return this.getAttribute("data-original-title") || this.getAttribute("title");
+        })
+        .attr("data-original-title", null)
+        .select(".tooltip")
+        .remove();
+    };
+
+    function setup() {
+      var root = d3.select(this),
+          animate = animation.apply(this, arguments),
+          tip = root.append("div")
+            .attr("class", "tooltip");
+
+      if (animate) {
+        tip.classed("fade", true);
+      }
+
+      // TODO "inside" checks?
+
+      tip.append("div")
+        .attr("class", "tooltip-arrow");
+      tip.append("div")
+        .attr("class", "tooltip-inner");
+
+      var place = placement.apply(this, arguments);
+      tip.classed(place, true);
+
+      root.on(over, show);
+      root.on(out, hide);
+    }
+
+    function show() {
+      var root = d3.select(this),
+          content = title.apply(this, arguments),
+          tip = root.select(".tooltip")
+            .classed("in", true),
+          markup = html.apply(this, arguments),
+          innercontent = tip.select(".tooltip-inner")[markup ? "html" : "text"](content),
+          place = placement.apply(this, arguments),
+          outer = getPosition(root.node()),
+          inner = getPosition(tip.node()),
+          pos;
+
+      switch (place) {
+        case "top":
+          pos = {x: outer.x + (outer.w - inner.w) / 2, y: outer.y - inner.h};
+          break;
+        case "right":
+          pos = {x: outer.x + outer.w, y: outer.y + (outer.h - inner.h) / 2};
+          break;
+        case "left":
+          pos = {x: outer.x - inner.w, y: outer.y + (outer.h - inner.h) / 2};
+          break;
+        case "bottom":
+          pos = {x: outer.x + (outer.w - inner.w) / 2, y: outer.y + outer.h};
+          break;
+      }
+
+      tip.style(pos ?
+        {left: ~~pos.x + "px", top: ~~pos.y + "px"} :
+        {left: null, top: null});
+
+      this.tooltipVisible = true;
+    }
+
+    function hide() {
+      d3.select(this).select(".tooltip")
+        .classed("in", false);
+
+      this.tooltipVisible = false;
+    }
+
+    function toggle() {
+      if (this.tooltipVisible) {
+        hide.apply(this, arguments);
+      } else {
+        show.apply(this, arguments);
+      }
+    }
+
+    return tooltip;
+  };
+
+  function getPosition(node) {
+    return {
+      x: node.offsetLeft,
+      y: node.offsetTop,
+      w: node.offsetWidth,
+      h: node.offsetHeight
+    };
+  }
+
+})(this);
diff --git a/js/lib/d3-compat.js b/js/lib/d3-compat.js
new file mode 100644
index 000000000..88a8fafe7
--- /dev/null
+++ b/js/lib/d3-compat.js
@@ -0,0 +1,48 @@
+(function() {
+
+  // get a reference to the d3.selection prototype,
+  // and keep a reference to the old d3.selection.on
+  var d3_selectionPrototype = d3.selection.prototype,
+      d3_on = d3_selectionPrototype.on;
+
+  // our shims are organized by event:
+  // "desired-event": ["shimmed-event", wrapperFunction]
+  var shims = {
+    "mouseenter": ["mouseover", relatedTarget],
+    "mouseleave": ["mouseout", relatedTarget]
+  };
+
+  // rewrite the d3.selection.on function to shim the events with wrapped
+  // callbacks
+  d3_selectionPrototype.on = function(evt, callback, useCapture) {
+    var bits = evt.split("."),
+        type = bits.shift(),
+        shim = shims[type];
+    if (shim) {
+      evt = bits.length ? [shim[0], bits].join(".") : shim[0];
+      if (typeof callback === "function") {
+        callback = shim[1](callback);
+      }
+      return d3_on.call(this, evt, callback, useCapture);
+    } else {
+      return d3_on.apply(this, arguments);
+    } 
+  };
+
+  function relatedTarget(callback) {
+    return function() {
+      var related = d3.event.relatedTarget;
+      if (this === related || childOf(this, related)) {
+        return undefined;
+      }
+      return callback.apply(this, arguments);
+    };
+  }
+
+  function childOf(p, c) {
+    if (p === c) return false;
+    while (c && c !== p) c = c.parentNode;
+    return c === p;
+  }
+
+})();