diff --git a/src/ol/layer/layer.js b/src/ol/layer/layer.js
index 18ec52032a..fae4420727 100644
--- a/src/ol/layer/layer.js
+++ b/src/ol/layer/layer.js
@@ -68,17 +68,17 @@ ol.layer.Layer.prototype.getSource = function() {
 };
 
 
+/**
+  * @inheritDoc
+  */
+ol.layer.Layer.prototype.getSourceState = function() {
+  return this.getSource().getState();
+};
+
+
 /**
  * @private
  */
 ol.layer.Layer.prototype.handleSourceChange_ = function() {
   this.dispatchChangeEvent();
 };
-
-
-/**
- * @inheritDoc
- */
-ol.layer.Layer.prototype.isReady = function() {
-  return this.getSource().isReady();
-};
diff --git a/src/ol/layer/layerbase.js b/src/ol/layer/layerbase.js
index 3af07a06d1..a6f590de07 100644
--- a/src/ol/layer/layerbase.js
+++ b/src/ol/layer/layerbase.js
@@ -7,6 +7,7 @@ goog.require('goog.events.EventType');
 goog.require('goog.math');
 goog.require('goog.object');
 goog.require('ol.Object');
+goog.require('ol.source.State');
 
 
 /**
@@ -29,8 +30,8 @@ ol.layer.LayerProperty = {
  *            contrast: number,
  *            hue: number,
  *            opacity: number,
- *            ready: boolean,
  *            saturation: number,
+ *            sourceState: ol.source.State,
  *            visible: boolean,
  *            maxResolution: number,
  *            minResolution: number}}
@@ -142,8 +143,8 @@ ol.layer.Base.prototype.getLayerState = function() {
   var contrast = this.getContrast();
   var hue = this.getHue();
   var opacity = this.getOpacity();
-  var ready = this.isReady();
   var saturation = this.getSaturation();
+  var sourceState = this.getSourceState();
   var visible = this.getVisible();
   var maxResolution = this.getMaxResolution();
   var minResolution = this.getMinResolution();
@@ -152,8 +153,8 @@ ol.layer.Base.prototype.getLayerState = function() {
     contrast: goog.isDef(contrast) ? Math.max(contrast, 0) : 1,
     hue: goog.isDef(hue) ? hue : 0,
     opacity: goog.isDef(opacity) ? goog.math.clamp(opacity, 0, 1) : 1,
-    ready: ready,
     saturation: goog.isDef(saturation) ? Math.max(saturation, 0) : 1,
+    sourceState: sourceState,
     visible: goog.isDef(visible) ? !!visible : true,
     maxResolution: goog.isDef(maxResolution) ? maxResolution : Infinity,
     minResolution: goog.isDef(minResolution) ? Math.max(minResolution, 0) : 0
@@ -232,6 +233,12 @@ goog.exportProperty(
     ol.layer.Base.prototype.getSaturation);
 
 
+/**
+ * @return {ol.source.State} Source state.
+ */
+ol.layer.Base.prototype.getSourceState = goog.abstractMethod;
+
+
 /**
  * @return {boolean} Visible.
  */
@@ -248,7 +255,7 @@ goog.exportProperty(
  * @protected
  */
 ol.layer.Base.prototype.handleLayerChange = function() {
-  if (this.getVisible() && this.isReady()) {
+  if (this.getVisible() && this.getSourceState() == ol.source.State.READY) {
     this.dispatchChangeEvent();
   }
 };
@@ -258,18 +265,12 @@ ol.layer.Base.prototype.handleLayerChange = function() {
  * @protected
  */
 ol.layer.Base.prototype.handleLayerVisibleChange = function() {
-  if (this.isReady()) {
+  if (this.getSourceState() == ol.source.State.READY) {
     this.dispatchChangeEvent();
   }
 };
 
 
-/**
- * @return {boolean} Is ready.
- */
-ol.layer.Base.prototype.isReady = goog.abstractMethod;
-
-
 /**
  * Adjust the layer brightness.  A value of -1 will render the layer completely
  * black.  A value of 0 will leave the brightness unchanged.  A value of 1 will
diff --git a/src/ol/layer/layergroup.js b/src/ol/layer/layergroup.js
index 9e37389f54..7336f682a4 100644
--- a/src/ol/layer/layergroup.js
+++ b/src/ol/layer/layergroup.js
@@ -11,6 +11,7 @@ goog.require('ol.CollectionEvent');
 goog.require('ol.CollectionEventType');
 goog.require('ol.Object');
 goog.require('ol.layer.Base');
+goog.require('ol.source.State');
 
 
 /**
@@ -205,6 +206,7 @@ ol.layer.Group.prototype.getLayerStatesArray = function(opt_obj) {
     layerState.hue += ownLayerState.hue;
     layerState.opacity *= ownLayerState.opacity;
     layerState.saturation *= ownLayerState.saturation;
+    layerState.sourceState = this.getSourceState();
     layerState.visible = layerState.visible && ownLayerState.visible;
     layerState.maxResolution = Math.min(
         layerState.maxResolution, ownLayerState.maxResolution);
@@ -219,9 +221,31 @@ ol.layer.Group.prototype.getLayerStatesArray = function(opt_obj) {
 /**
  * @inheritDoc
  */
-ol.layer.Group.prototype.isReady = function() {
-  return null === goog.array.find(
-      this.getLayers().getArray(), function(elt, index, array) {
-        return !elt.isReady();
-      });
+ol.layer.Group.prototype.getSourceState = function() {
+  // Return the layer group's source state based on the best source state of its
+  // children:
+  // - if any child is READY, return READY
+  // - otherwise, if any child is LOADING, return LOADING
+  // - otherwise, all children must be in ERROR, return ERROR
+  // - otherwise, there are no children, return READY
+  var layerSourceStates = [0, 0, 0];
+  var layers = this.getLayers().getArray();
+  var n = layers.length;
+  var i;
+  for (i = 0; i < n; ++i) {
+    var layerSourceState = layers[i].getSourceState();
+    goog.asserts.assert(layerSourceState < layerSourceStates.length);
+    ++layerSourceStates[layerSourceState];
+  }
+  if (layerSourceStates[ol.source.State.READY]) {
+    return ol.source.State.READY;
+  } else if (layerSourceStates[ol.source.State.LOADING]) {
+    return ol.source.State.LOADING;
+  } else if (layerSourceStates[ol.source.State.ERROR]) {
+    goog.asserts.assert(layerSourceStates[ol.source.State.ERROR] == n);
+    return ol.source.State.ERROR;
+  } else {
+    goog.asserts.assert(n === 0);
+    return ol.source.State.READY;
+  }
 };
diff --git a/src/ol/renderer/canvas/canvasmaprenderer.js b/src/ol/renderer/canvas/canvasmaprenderer.js
index f081990b78..2795c8ab3c 100644
--- a/src/ol/renderer/canvas/canvasmaprenderer.js
+++ b/src/ol/renderer/canvas/canvasmaprenderer.js
@@ -17,6 +17,7 @@ goog.require('ol.renderer.canvas.ImageLayer');
 goog.require('ol.renderer.canvas.TileLayer');
 goog.require('ol.renderer.canvas.VectorLayer');
 goog.require('ol.size');
+goog.require('ol.source.State');
 
 
 
@@ -121,7 +122,8 @@ ol.renderer.canvas.Map.prototype.renderFrame = function(frameState) {
     layer = layersArray[i];
     layerRenderer = this.getLayerRenderer(layer);
     layerState = layerStates[goog.getUid(layer)];
-    if (!layerState.visible || !layerState.ready ||
+    if (!layerState.visible ||
+        layerState.sourceState != ol.source.State.READY ||
         viewResolution >= layerState.maxResolution ||
         viewResolution < layerState.minResolution) {
       continue;
diff --git a/src/ol/renderer/dom/dommaprenderer.js b/src/ol/renderer/dom/dommaprenderer.js
index 1da6b24a6c..3a8dfc49d7 100644
--- a/src/ol/renderer/dom/dommaprenderer.js
+++ b/src/ol/renderer/dom/dommaprenderer.js
@@ -10,6 +10,7 @@ goog.require('ol.layer.Tile');
 goog.require('ol.renderer.Map');
 goog.require('ol.renderer.dom.ImageLayer');
 goog.require('ol.renderer.dom.TileLayer');
+goog.require('ol.source.State');
 
 
 
@@ -84,7 +85,7 @@ ol.renderer.dom.Map.prototype.renderFrame = function(frameState) {
     layer = layersArray[i];
     layerRenderer = this.getLayerRenderer(layer);
     layerState = frameState.layerStates[goog.getUid(layer)];
-    if (layerState.ready) {
+    if (layerState.sourceState == ol.source.State.READY) {
       layerRenderer.renderFrame(frameState, layerState);
     }
   }
diff --git a/src/ol/renderer/layerrenderer.js b/src/ol/renderer/layerrenderer.js
index 65d3d50af6..8dc5cf489a 100644
--- a/src/ol/renderer/layerrenderer.js
+++ b/src/ol/renderer/layerrenderer.js
@@ -10,6 +10,7 @@ goog.require('ol.TileState');
 goog.require('ol.layer.Layer');
 goog.require('ol.layer.LayerState');
 goog.require('ol.source.Source');
+goog.require('ol.source.State');
 goog.require('ol.source.Tile');
 
 
@@ -113,7 +114,7 @@ ol.renderer.Layer.prototype.renderFrame = goog.abstractMethod;
  */
 ol.renderer.Layer.prototype.renderIfReadyAndVisible = function() {
   var layer = this.getLayer();
-  if (layer.getVisible() && layer.isReady()) {
+  if (layer.getVisible() && layer.getSourceState() == ol.source.State.READY) {
     this.getMap().render();
   }
 };
diff --git a/src/ol/renderer/webgl/webglmaprenderer.js b/src/ol/renderer/webgl/webglmaprenderer.js
index f3b1876393..0d0e499cc2 100644
--- a/src/ol/renderer/webgl/webglmaprenderer.js
+++ b/src/ol/renderer/webgl/webglmaprenderer.js
@@ -27,6 +27,7 @@ goog.require('ol.renderer.webgl.VectorLayer2');
 goog.require('ol.renderer.webgl.map.shader.Color');
 goog.require('ol.renderer.webgl.map.shader.Default');
 goog.require('ol.size');
+goog.require('ol.source.State');
 goog.require('ol.structs.Buffer');
 goog.require('ol.structs.IntegerSet');
 goog.require('ol.structs.LRUCache');
@@ -557,7 +558,8 @@ ol.renderer.webgl.Map.prototype.renderFrame = function(frameState) {
     layer = layersArray[i];
     layerRenderer = this.getLayerRenderer(layer);
     layerState = frameState.layerStates[goog.getUid(layer)];
-    if (layerState.visible && layerState.ready &&
+    if (layerState.visible &&
+        layerState.sourceState == ol.source.State.READY &&
         viewResolution < layerState.maxResolution &&
         viewResolution >= layerState.minResolution) {
       layerRenderer.renderFrame(frameState, layerState);
@@ -585,7 +587,8 @@ ol.renderer.webgl.Map.prototype.renderFrame = function(frameState) {
   for (i = 0, ii = layersArray.length; i < ii; ++i) {
     layer = layersArray[i];
     layerState = frameState.layerStates[goog.getUid(layer)];
-    if (!layerState.visible || !layerState.ready ||
+    if (!layerState.visible ||
+        layerState.sourceState != ol.source.State.READY ||
         viewResolution >= layerState.maxResolution ||
         viewResolution < layerState.minResolution) {
       continue;
diff --git a/src/ol/source/bingmapssource.js b/src/ol/source/bingmapssource.js
index 29b3b456ea..54816e51f9 100644
--- a/src/ol/source/bingmapssource.js
+++ b/src/ol/source/bingmapssource.js
@@ -9,6 +9,7 @@ goog.require('ol.TileRange');
 goog.require('ol.TileUrlFunction');
 goog.require('ol.extent');
 goog.require('ol.proj');
+goog.require('ol.source.State');
 goog.require('ol.source.TileImage');
 goog.require('ol.tilegrid.XYZ');
 
@@ -25,6 +26,7 @@ ol.source.BingMaps = function(options) {
     crossOrigin: 'anonymous',
     opaque: true,
     projection: ol.proj.get('EPSG:3857'),
+    state: ol.source.State.LOADING,
     tileLoadFunction: options.tileLoadFunction
   });
 
@@ -34,12 +36,6 @@ ol.source.BingMaps = function(options) {
    */
   this.culture_ = goog.isDef(options.culture) ? options.culture : 'en-us';
 
-  /**
-   * @private
-   * @type {boolean}
-   */
-  this.ready_ = false;
-
   var uri = new goog.Uri(
       '//dev.virtualearth.net/REST/v1/Imagery/Metadata/' + options.style);
   var jsonp = new goog.net.Jsonp(uri, 'jsonp');
@@ -139,16 +135,6 @@ ol.source.BingMaps.prototype.handleImageryMetadataResponse =
 
   this.setLogo(brandLogoUri);
 
-  this.ready_ = true;
-
-  this.dispatchChangeEvent();
+  this.setState(ol.source.State.READY);
 
 };
-
-
-/**
- * @inheritDoc
- */
-ol.source.BingMaps.prototype.isReady = function() {
-  return this.ready_;
-};
diff --git a/src/ol/source/source.js b/src/ol/source/source.js
index aa6d20caea..83a4b2ae6d 100644
--- a/src/ol/source/source.js
+++ b/src/ol/source/source.js
@@ -1,18 +1,29 @@
 goog.provide('ol.source.Source');
+goog.provide('ol.source.State');
 
 goog.require('goog.events.EventTarget');
 goog.require('goog.events.EventType');
-goog.require('goog.functions');
 goog.require('ol.Attribution');
 goog.require('ol.Extent');
 goog.require('ol.proj');
 
 
+/**
+ * @enum {number}
+ */
+ol.source.State = {
+  LOADING: 0,
+  READY: 1,
+  ERROR: 2
+};
+
+
 /**
  * @typedef {{attributions: (Array.<ol.Attribution>|undefined),
  *            extent: (ol.Extent|undefined),
  *            logo: (string|undefined),
- *            projection: ol.proj.ProjectionLike}}
+ *            projection: ol.proj.ProjectionLike,
+ *            state: (ol.source.State|undefined)}}
  */
 ol.source.SourceOptions;
 
@@ -54,6 +65,13 @@ ol.source.Source = function(options) {
    */
   this.logo_ = options.logo;
 
+  /**
+   * @private
+   * @type {ol.source.State}
+   */
+  this.state_ = goog.isDef(options.state) ?
+      options.state : ol.source.State.READY;
+
   /**
    * @private
    * @type {number}
@@ -120,9 +138,11 @@ ol.source.Source.prototype.getRevision = function() {
 
 
 /**
- * @return {boolean} Is ready.
+ * @return {ol.source.State} State.
  */
-ol.source.Source.prototype.isReady = goog.functions.TRUE;
+ol.source.Source.prototype.getState = function() {
+  return this.state_;
+};
 
 
 /**
@@ -149,6 +169,16 @@ ol.source.Source.prototype.setLogo = function(logo) {
 };
 
 
+/**
+ * @param {ol.source.State} state State.
+ * @protected
+ */
+ol.source.Source.prototype.setState = function(state) {
+  this.state_ = state;
+  this.dispatchChangeEvent();
+};
+
+
 /**
  * @param {ol.proj.Projection} projection Projetion.
  */
diff --git a/src/ol/source/tilejsonsource.js b/src/ol/source/tilejsonsource.js
index 879e68d4a5..e31b9d83e0 100644
--- a/src/ol/source/tilejsonsource.js
+++ b/src/ol/source/tilejsonsource.js
@@ -15,6 +15,7 @@ goog.require('ol.TileRange');
 goog.require('ol.TileUrlFunction');
 goog.require('ol.extent');
 goog.require('ol.proj');
+goog.require('ol.source.State');
 goog.require('ol.source.TileImage');
 goog.require('ol.tilegrid.XYZ');
 
@@ -46,15 +47,10 @@ ol.source.TileJSON = function(options) {
   goog.base(this, {
     crossOrigin: options.crossOrigin,
     projection: ol.proj.get('EPSG:3857'),
+    state: ol.source.State.LOADING,
     tileLoadFunction: options.tileLoadFunction
   });
 
-  /**
-   * @private
-   * @type {boolean}
-   */
-  this.ready_ = false;
-
   /**
    * @private
    * @type {!goog.async.Deferred}
@@ -118,16 +114,6 @@ ol.source.TileJSON.prototype.handleTileJSONResponse = function() {
     ]);
   }
 
-  this.ready_ = true;
-
-  this.dispatchChangeEvent();
+  this.setState(ol.source.State.READY);
 
 };
-
-
-/**
- * @inheritDoc
- */
-ol.source.TileJSON.prototype.isReady = function() {
-  return this.ready_;
-};
diff --git a/test/spec/ol/layer/layer.test.js b/test/spec/ol/layer/layer.test.js
index 473fa96480..bcb52a8be7 100644
--- a/test/spec/ol/layer/layer.test.js
+++ b/test/spec/ol/layer/layer.test.js
@@ -54,7 +54,7 @@ describe('ol.layer.Layer', function() {
         opacity: 1,
         saturation: 1,
         visible: true,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: Infinity,
         minResolution: 0
       });
@@ -96,7 +96,7 @@ describe('ol.layer.Layer', function() {
         opacity: 0.5,
         saturation: 5,
         visible: false,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: 500,
         minResolution: 0.25
       });
@@ -138,7 +138,7 @@ describe('ol.layer.Layer', function() {
         opacity: 0.3,
         saturation: 0.3,
         visible: false,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: 500,
         minResolution: 0.25
       });
@@ -158,7 +158,7 @@ describe('ol.layer.Layer', function() {
         opacity: 0,
         saturation: 0,
         visible: false,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: Infinity,
         minResolution: 0
       });
@@ -176,7 +176,7 @@ describe('ol.layer.Layer', function() {
         opacity: 1,
         saturation: 42,
         visible: true,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: Infinity,
         minResolution: 0
       });
@@ -359,3 +359,4 @@ goog.require('goog.dispose');
 goog.require('ol.layer.Layer');
 goog.require('ol.proj');
 goog.require('ol.source.Source');
+goog.require('ol.source.State');
diff --git a/test/spec/ol/layer/layergroup.test.js b/test/spec/ol/layer/layergroup.test.js
index 74f9755e46..5946ec1d20 100644
--- a/test/spec/ol/layer/layergroup.test.js
+++ b/test/spec/ol/layer/layergroup.test.js
@@ -50,7 +50,7 @@ describe('ol.layer.Group', function() {
         opacity: 1,
         saturation: 1,
         visible: true,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: Infinity,
         minResolution: 0
       });
@@ -98,7 +98,7 @@ describe('ol.layer.Group', function() {
         opacity: 0.5,
         saturation: 5,
         visible: false,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: 500,
         minResolution: 0.25
       });
@@ -140,7 +140,7 @@ describe('ol.layer.Group', function() {
         opacity: 0.3,
         saturation: 0.3,
         visible: false,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: 500,
         minResolution: 0.25
       });
@@ -160,7 +160,7 @@ describe('ol.layer.Group', function() {
         opacity: 0,
         saturation: 0,
         visible: false,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: Infinity,
         minResolution: 0
       });
@@ -178,7 +178,7 @@ describe('ol.layer.Group', function() {
         opacity: 1,
         saturation: 42,
         visible: true,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: Infinity,
         minResolution: 0
       });
@@ -297,7 +297,7 @@ describe('ol.layer.Group', function() {
         opacity: 0.25,
         saturation: 25,
         visible: false,
-        ready: true,
+        sourceState: ol.source.State.READY,
         maxResolution: 150,
         minResolution: 0.25
       });
@@ -316,4 +316,5 @@ goog.require('goog.dispose');
 goog.require('ol.layer.Layer');
 goog.require('ol.layer.Group');
 goog.require('ol.source.Source');
+goog.require('ol.source.State');
 goog.require('ol.Collection');