diff --git a/core/dropdowndiv.js b/core/dropdowndiv.js
index 426bdab04..501104d01 100644
--- a/core/dropdowndiv.js
+++ b/core/dropdowndiv.js
@@ -224,7 +224,6 @@ Blockly.DropDownDiv.showPositionedByBlock = function(field, block,
   return Blockly.DropDownDiv.show(field, primaryX, primaryY, secondaryX, secondaryY, opt_onHide);
 };
 
-
 /**
  * Shortcut to show and place the drop-down with positioning determined
  * by a particular field. The primary position will be below the field,
@@ -257,7 +256,6 @@ Blockly.DropDownDiv.showPositionedByField = function(owner,
       owner, primaryX, primaryY, secondaryX, secondaryY, opt_onHide);
 };
 
-
 /**
  * Show and place the drop-down.
  * The drop-down is placed with an absolute "origin point" (x, y) - i.e.,
@@ -281,11 +279,15 @@ Blockly.DropDownDiv.show = function(owner, primaryX, primaryY,
   var metrics = Blockly.DropDownDiv.getPositionMetrics(primaryX, primaryY,
       secondaryX, secondaryY);
   // Update arrow CSS.
-  Blockly.DropDownDiv.arrow_.style.transform = 'translate(' +
-      metrics.arrowX + 'px,' + metrics.arrowY + 'px) rotate(45deg)';
-  Blockly.DropDownDiv.arrow_.setAttribute('class', metrics.arrowAtTop ?
+  if (metrics.arrowVisible) {
+    Blockly.DropDownDiv.arrow_.style.display = '';
+    Blockly.DropDownDiv.arrow_.style.transform = 'translate(' +
+      metrics.arrowX + 'px,' + metrics.arrowY + 'px) rotate(45deg)'; // rotate(45deg)
+    Blockly.DropDownDiv.arrow_.setAttribute('class', metrics.arrowAtTop ?
       'blocklyDropDownArrow arrowTop' : 'blocklyDropDownArrow arrowBottom');
-  Blockly.DropDownDiv.arrow_.style.display = metrics.arrowVisible ? '' : 'none';
+  } else {
+    Blockly.DropDownDiv.arrow_.style.display = 'none';
+  }
 
   // When we change `translate` multiple times in close succession,
   // Chrome may choose to wait and apply them all at once.
@@ -309,6 +311,8 @@ Blockly.DropDownDiv.show = function(owner, primaryX, primaryY,
  * @private
  */
 Blockly.DropDownDiv.getBoundsInfo_ = function() {
+  // TODO (#2744): Account for toolboxes.
+
   var boundPosition = Blockly.DropDownDiv.boundsElement_.getBoundingClientRect();
   var boundSize = goog.style.getSize(Blockly.DropDownDiv.boundsElement_);
 
@@ -325,91 +329,177 @@ Blockly.DropDownDiv.getBoundsInfo_ = function() {
 /**
  * Helper to position the drop-down and the arrow, maintaining bounds.
  * See explanation of origin points in Blockly.DropDownDiv.show.
- * @param {number} primaryX Desired origin point x, in absolute px
- * @param {number} primaryY Desired origin point y, in absolute px
- * @param {number} secondaryX Secondary/alternative origin point x, in absolute px
- * @param {number} secondaryY Secondary/alternative origin point y, in absolute px
- * @return {Object} Various final metrics, including rendered positions for drop-down and arrow.
+ * @param {number} primaryX Desired origin point x, in absolute px.
+ * @param {number} primaryY Desired origin point y, in absolute px.
+ * @param {number} secondaryX Secondary/alternative origin point x,
+ *    in absolute px.
+ * @param {number} secondaryY Secondary/alternative origin point y,
+ *    in absolute px.
+ * @return {Object} Various final metrics, including rendered positions
+ *    for drop-down and arrow.
  */
 Blockly.DropDownDiv.getPositionMetrics = function(primaryX, primaryY,
     secondaryX, secondaryY) {
   var boundsInfo = Blockly.DropDownDiv.getBoundsInfo_();
-  var div = Blockly.DropDownDiv.DIV_;
-  var divSize = goog.style.getSize(div);
+  var divSize = goog.style.getSize(Blockly.DropDownDiv.DIV_);
 
-  // First decide if we will render at primary or secondary position
-  // i.e., above or below
-  // renderX, renderY will eventually be the final rendered position of the box.
-  var renderX, renderY, renderedSecondary, renderedTertiary;
-  // Can the div fit inside the bounds if we render below the primary point?
-  if (primaryY + divSize.height > boundsInfo.bottom) {
-    // We can't fit below in terms of y. Can we fit above?
-    if (secondaryY - divSize.height < boundsInfo.top) {
-      // We also can't fit above, so just render at the top of the screen.
-      renderX = primaryX;
-      renderY = 0;
-      renderedSecondary = false;
-      renderedTertiary = true;
-    } else {
-      // We can fit above, render secondary
-      renderX = secondaryX;
-      renderY = secondaryY - divSize.height - Blockly.DropDownDiv.PADDING_Y;
-      renderedSecondary = true;
-    }
-  } else {
-    // We can fit below, render primary
-    renderX = primaryX;
-    renderY = primaryY + Blockly.DropDownDiv.PADDING_Y;
-    renderedSecondary = false;
+  // Can we fit in-bounds below the target?
+  if (primaryY + divSize.height < boundsInfo.bottom) {
+    return Blockly.DropDownDiv.getPositionBelowMetrics(
+        primaryX, primaryY, boundsInfo, divSize);
+  }
+  // Can we fit in-bounds above the target?
+  if (secondaryY - divSize.height > boundsInfo.top) {
+    return Blockly.DropDownDiv.getPositionAboveMetrics(
+        secondaryX, secondaryY, boundsInfo, divSize);
+  }
+  // Can we fit outside the workspace bounds (but inside the window) below?
+  if (primaryY + divSize.height < document.documentElement.clientHeight) {
+    return Blockly.DropDownDiv.getPositionBelowMetrics(
+        primaryX, primaryY, boundsInfo, divSize);
+  }
+  // Can we fit outside the workspace bounds (but inside the window) above?
+  if (secondaryY - divSize.height > document.documentElement.clientTop) {
+    return Blockly.DropDownDiv.getPositionAboveMetrics(
+        secondaryX, secondaryY, boundsInfo, divSize);
   }
 
-  var centerX = renderX;
-  // The dropdown's X position is at the top-left of the dropdown rect, but the
-  // dropdown should appear centered relative to the desired origin point.
-  renderX -= divSize.width / 2;
-  // Fit horizontally in the bounds.
-  renderX = Blockly.utils.math.clamp(
-      boundsInfo.left, renderX, boundsInfo.right - divSize.width);
+  // Last resort, render at top of page.
+  return Blockly.DropDownDiv.getPositionTopOfPageMetrics(
+      primaryX, boundsInfo, divSize);
+};
 
-  // Calculate the absolute arrow X. The arrow wants to be as close to the
-  // origin point as possible. The arrow may not be centered in the dropdown div.
-  var absoluteArrowX = centerX - Blockly.DropDownDiv.ARROW_SIZE / 2;
-  // Keep in overall bounds
-  absoluteArrowX = Blockly.utils.math.clamp(
-      boundsInfo.left, absoluteArrowX, boundsInfo.right);
+/**
+ * Get the metrics for positioning the div below the source.
+ * @param {number} primaryX Desired origin point x, in absolute px.
+ * @param {number} primaryY Desired origin point y, in absolute px.
+ * @param {!Object} boundsInfo An object containing size information about the
+ *    bounding element (bounding box and width/height).
+ * @param {!Object} divSize An object containing information about the size
+ *    of the DropDownDiv (width & height).
+ * @return {Object} Various final metrics, including rendered positions
+ *    for drop-down and arrow.
+ */
+Blockly.DropDownDiv.getPositionBelowMetrics = function(
+    primaryX, primaryY, boundsInfo, divSize) {
 
-  // Convert the arrow position to be relative to the top left corner of the div.
-  var relativeArrowX = absoluteArrowX - renderX;
+  var xCoords = Blockly.DropDownDiv.getPositionX(
+      primaryX, boundsInfo.left, boundsInfo.right, divSize.width);
 
-  // Pad the arrow by some pixels, primarily so that it doesn't render on top
-  // of a rounded border.
-  relativeArrowX = Blockly.utils.math.clamp(
-      Blockly.DropDownDiv.ARROW_HORIZONTAL_PADDING,
-      relativeArrowX,
-      divSize.width - Blockly.DropDownDiv.ARROW_HORIZONTAL_PADDING -
-          Blockly.DropDownDiv.ARROW_SIZE);
-
-  var arrowY = (renderedSecondary) ?
-      divSize.height - Blockly.DropDownDiv.BORDER_SIZE : 0;
-  arrowY -= (Blockly.DropDownDiv.ARROW_SIZE / 2) +
-      Blockly.DropDownDiv.BORDER_SIZE;
-
-  var initialY;
-  if (renderedSecondary) {
-    initialY = secondaryY - divSize.height; // No padding on Y
-  } else {
-    initialY = primaryY; // No padding on Y
-  }
+  var arrowY = -(Blockly.DropDownDiv.ARROW_SIZE / 2
+      + Blockly.DropDownDiv.BORDER_SIZE);
+  var finalY = primaryY + Blockly.DropDownDiv.PADDING_Y;
 
   return {
-    initialX: renderX, // X position remains constant during animation.
-    initialY : initialY,
-    finalX: renderX,
-    finalY: renderY,
-    arrowX: relativeArrowX,
+    initialX: xCoords.divX,
+    initialY : primaryY,
+    finalX: xCoords.divX, // X position remains constant during animation.
+    finalY: finalY,
+    arrowX: xCoords.arrowX,
     arrowY: arrowY,
-    arrowAtTop: !renderedSecondary,
-    arrowVisible: !renderedTertiary
+    arrowAtTop: true,
+    arrowVisible: true
+  };
+};
+
+/**
+ * Get the metrics for positioning the div above the source.
+ * @param {number} secondaryX Secondary/alternative origin point x,
+ *    in absolute px.
+ * @param {number} secondaryY Secondary/alternative origin point y,
+ *    in absolute px.
+ * @param {!Object} boundsInfo An object containing size information about the
+ *    bounding element (bounding box and width/height).
+ * @param {!Object} divSize An object containing information about the size
+ *    of the DropDownDiv (width & height).
+ * @return {Object} Various final metrics, including rendered positions
+ *    for drop-down and arrow.
+ */
+Blockly.DropDownDiv.getPositionAboveMetrics = function(
+    secondaryX, secondaryY, boundsInfo, divSize) {
+
+  var xCoords = Blockly.DropDownDiv.getPositionX(
+      secondaryX, boundsInfo.left, boundsInfo.right, divSize.width);
+
+  var arrowY = divSize.height - (Blockly.DropDownDiv.BORDER_SIZE * 2)
+      - (Blockly.DropDownDiv.ARROW_SIZE / 2);
+  var finalY = secondaryY - divSize.height - Blockly.DropDownDiv.PADDING_Y;
+  var initialY = secondaryY - divSize.height; // No padding on Y
+
+  return {
+    initialX: xCoords.divX,
+    initialY : initialY,
+    finalX: xCoords.divX, // X position remains constant during animation.
+    finalY: finalY,
+    arrowX: xCoords.arrowX,
+    arrowY: arrowY,
+    arrowAtTop: false,
+    arrowVisible: true
+  };
+};
+
+/**
+ * Get the metrics for positioning the div at the top of the page.
+ * @param {number} sourceX Desired origin point x, in absolute px.
+ * @param {!Object} boundsInfo An object containing size information about the
+ *    bounding element (bounding box and width/height).
+ * @param {!Object} divSize An object containing information about the size
+ *    of the DropDownDiv (width & height).
+ * @return {Object} Various final metrics, including rendered positions
+ *    for drop-down and arrow.
+ */
+Blockly.DropDownDiv.getPositionTopOfPageMetrics = function(
+    sourceX, boundsInfo, divSize) {
+
+  var xCoords = Blockly.DropDownDiv.getPositionX(
+      sourceX, boundsInfo.left, boundsInfo.right, divSize.width);
+
+  // No need to provide arrow-specific information because it won't be visible.
+  return {
+    initialX: xCoords.divX,
+    initialY : 0,
+    finalX: xCoords.divX, // X position remains constant during animation.
+    finalY: 0,            // Y position remains constant during animation.
+    arrowVisible: false
+  };
+};
+
+/**
+ * Get the x positions for the left side of the DropDownDiv and the arrow,
+ * accounting for the bounds of the workspace.
+ * @param {number} sourceX Desired origin point x, in absolute px.
+ * @param {number} boundsLeft The left edge of the bounding element, in
+ *    absolute px.
+ * @param {number} boundsRight The right edge of the bounding element, in
+ *    absolute px.
+ * @param {number} divWidth The width of the div in px.
+ * @return {{divX: number, arrowX: number}} An object containing metrics for
+ *    the x positions of the left side of the DropDownDiv and the arrow.
+ */
+Blockly.DropDownDiv.getPositionX = function(
+    sourceX, boundsLeft, boundsRight, divWidth) {
+  var arrowX, divX;
+  arrowX = divX = sourceX;
+
+  // Offset the topLeft coord so that the dropdowndiv is centered.
+  divX -= divWidth / 2;
+  // Fit the dropdowndiv within the bounds of the workspace.
+  divX = Blockly.utils.math.clamp(boundsLeft, divX, boundsRight - divWidth);
+
+  // Offset the arrow coord so that the arrow is centered.
+  arrowX -= Blockly.DropDownDiv.ARROW_SIZE / 2;
+  // Convert the arrow position to be relative to the top left of the div.
+  var relativeArrowX = arrowX - divX;
+  var horizPadding = Blockly.DropDownDiv.ARROW_HORIZONTAL_PADDING;
+  // Clamp the arrow position so that it stays attached to the dropdowndiv.
+  relativeArrowX = Blockly.utils.math.clamp(
+      horizPadding,
+      relativeArrowX,
+      divWidth - horizPadding - Blockly.DropDownDiv.ARROW_SIZE);
+
+  return {
+    arrowX: relativeArrowX,
+    divX: divX
   };
 };
 
@@ -481,7 +571,6 @@ Blockly.DropDownDiv.hideWithoutAnimation = function() {
   }
 };
 
-
 /**
  * Set the dropdown div's position.
  * @param {number} initialX Initial Horizontal location
diff --git a/tests/mocha/dropdowndiv_test.js b/tests/mocha/dropdowndiv_test.js
new file mode 100644
index 000000000..c7f3a083a
--- /dev/null
+++ b/tests/mocha/dropdowndiv_test.js
@@ -0,0 +1,91 @@
+/**
+ * @license
+ * Visual Blocks Editor
+ *
+ * Copyright 2019 Google Inc.
+ * https://developers.google.com/blockly/
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+suite('DropDownDiv', function() {
+  suite('Positioning', function() {
+    setup(function() {
+      this.boundsStub = sinon.stub(Blockly.DropDownDiv, 'getBoundsInfo_')
+          .returns({
+            left: 0,
+            right: 100,
+            top: 0,
+            bottom: 100,
+            width: 100,
+            height: 100
+          });
+      this.sizeStub = sinon.stub(goog.style, 'getSize')
+          .returns({
+            width: 60,
+            height: 60
+          });
+      this.clientHeightStub = sinon.stub(document.documentElement, 'clientHeight')
+          .get(function() { return 1000; });
+      this.clientTopStub = sinon.stub(document.documentElement, 'clientTop')
+          .get(function() { return 0; });
+    });
+    teardown(function() {
+      this.boundsStub.restore();
+      this.sizeStub.restore();
+      this.clientHeightStub.restore();
+      this.clientTopStub.restore();
+    });
+    test('Below, in Bounds', function() {
+      var metrics = Blockly.DropDownDiv.getPositionMetrics(50, 0, 50, -10);
+      // "Above" in value actually means below in render.
+      chai.assert.isAtLeast(metrics.initialY, 0);
+      chai.assert.isAbove(metrics.finalY, 0);
+      chai.assert.isTrue(metrics.arrowVisible);
+      chai.assert.isTrue(metrics.arrowAtTop);
+    });
+    test('Above, in Bounds', function() {
+      var metrics = Blockly.DropDownDiv.getPositionMetrics(50, 100, 50, 90);
+      // "Below" in value actually means above in render.
+      chai.assert.isAtMost(metrics.initialY, 100);
+      chai.assert.isBelow(metrics.finalY, 100);
+      chai.assert.isTrue(metrics.arrowVisible);
+      chai.assert.isFalse(metrics.arrowAtTop);
+    });
+    test('Below, out of Bounds', function() {
+      var metrics = Blockly.DropDownDiv.getPositionMetrics(50, 60, 50, 50);
+      // "Above" in value actually means below in render.
+      chai.assert.isAtLeast(metrics.initialY, 60);
+      chai.assert.isAbove(metrics.finalY, 60);
+      chai.assert.isTrue(metrics.arrowVisible);
+      chai.assert.isTrue(metrics.arrowAtTop);
+    });
+    test('Above, in Bounds', function() {
+      var metrics = Blockly.DropDownDiv.getPositionMetrics(50, 100, 50, 90);
+      // "Below" in value actually means above in render.
+      chai.assert.isAtMost(metrics.initialY, 100);
+      chai.assert.isBelow(metrics.finalY, 100);
+      chai.assert.isTrue(metrics.arrowVisible);
+      chai.assert.isFalse(metrics.arrowAtTop);
+    });
+    test('No Solution, Render At Top', function() {
+      this.clientHeightStub.get(function() { return 100; });
+      var metrics = Blockly.DropDownDiv.getPositionMetrics(50, 60, 50, 50);
+      // "Above" in value actually means below in render.
+      chai.assert.equal(metrics.initialY, 0);
+      chai.assert.equal(metrics.finalY, 0);
+      chai.assert.isFalse(metrics.arrowVisible);
+      chai.assert.isNotOk(metrics.arrowAtTop);
+    });
+  });
+});
diff --git a/tests/mocha/index.html b/tests/mocha/index.html
index e338cd5b1..9cbe5c1f6 100644
--- a/tests/mocha/index.html
+++ b/tests/mocha/index.html
@@ -28,6 +28,7 @@
     <script src="block_test.js"></script>
     <script src="connection_test.js"></script>
     <script src="cursor_test.js"></script>
+    <script src="dropdowndiv_test.js"></script>
     <script src="event_test.js"></script>
     <script src="field_test.js"></script>
     <script src="field_angle_test.js"></script>