diff --git a/changelog.txt b/changelog.txt
index 98a94fd0..9649171b 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -39,6 +39,7 @@ OPENSEADRAGON CHANGELOG
 * Rect and Point toString() functions are now consistent: rounding values to nearest hundredth
 * Overlays appear in the DOM immediately on open or addOverlay (#507)
 * imageLoaderLimit now works (#544)
+* Added ajaxWithCredentials option (#543)
 
 1.2.0: (in progress)
 
diff --git a/src/openseadragon.js b/src/openseadragon.js
index 81028d19..dc7a5638 100644
--- a/src/openseadragon.js
+++ b/src/openseadragon.js
@@ -556,6 +556,7 @@
   *
   * @property {Boolean} [ajaxWithCredentials=false]
   *     Whether to set the withCredentials XHR flag for AJAX requests (when loading tile sources).
+  *     Note that this can be overridden at the {@link OpenSeadragon.TileSource} level.
   *
   */
 
@@ -1920,15 +1921,18 @@ window.OpenSeadragon = window.OpenSeadragon || function( options ){
 
         /**
          * Makes an AJAX request.
-         * @function
-         * @param {String} url - the url to request
-         * @param {Function} onSuccess - a function to call on a successful response
-         * @param {Function} onError - a function to call on when an error occurs
+         * @param {Object} options
+         * @param {String} options.url - the url to request
+         * @param {Function} options.success - a function to call on a successful response
+         * @param {Function} options.error - a function to call on when an error occurs
+         * @param {Boolean} [options.withCredentials=false] - whether to set the XHR's withCredentials
          * @throws {Error}
          */
         makeAjaxRequest: function( url, onSuccess, onError ) {
             var withCredentials;
 
+            // Note that our preferred API is that you pass in a single object; the named
+            // arguments are for legacy support.
             if( $.isPlainObject( url ) ){
                 onSuccess = url.success;
                 onError = url.error;
diff --git a/src/tilesource.js b/src/tilesource.js
index 8d6ab5fb..1c0d29d2 100644
--- a/src/tilesource.js
+++ b/src/tilesource.js
@@ -38,39 +38,46 @@
 /**
  * @class TileSource
  * @classdesc The TileSource contains the most basic implementation required to create a
- * smooth transition between layer in an image pyramid. It has only a single key
- * interface that must be implemented to complete it key functionality:
+ * smooth transition between layers in an image pyramid. It has only a single key
+ * interface that must be implemented to complete its key functionality:
  * 'getTileUrl'.  It also has several optional interfaces that can be
  * implemented if a new TileSource wishes to support configuration via a simple
  * object or array ('configure') and if the tile source supports or requires
- * configuration via retreival of a document on the network ala AJAX or JSONP,
+ * configuration via retrieval of a document on the network ala AJAX or JSONP,
  * ('getImageInfo').
  * <br/>
- * By default the image pyramid is split into N layers where the images longest
+ * By default the image pyramid is split into N layers where the image's longest
  * side in M (in pixels), where N is the smallest integer which satisfies
  *      <strong>2^(N+1) >= M</strong>.
  *
  * @memberof OpenSeadragon
  * @extends OpenSeadragon.EventSource
- * @param {Number|Object|Array|String} width
- *      If more than a single argument is supplied, the traditional use of
- *      positional parameters is supplied and width is expected to be the width
- *      source image at its max resolution in pixels.  If a single argument is supplied and
- *      it is an Object or Array, the construction is assumed to occur through
- *      the extending classes implementation of 'configure'.  Finally if only a
- *      single argument is supplied and it is a String, the extending class is
- *      expected to implement 'getImageInfo' and 'configure'.
- * @param {Number} height
+ * @param {Object} options
+ *      You can either specify a URL, or literally define the TileSource (by specifying
+ *      width, height, tileSize, tileOverlap, minLevel, and maxLevel). For the former,
+ *      the extending class is expected to implement 'getImageInfo' and 'configure'.
+ *      For the latter, the construction is assumed to occur through
+ *      the extending classes implementation of 'configure'.
+ * @param {String} [options.url]
+ *      The URL for the data necessary for this TileSource.
+ * @param {Function} [options.success]
+ *      A function to be called upon successful creation.
+ * @param {Boolean} [options.ajaxWithCredentials]
+ *      If this TileSource needs to make an AJAX call, this specifies whether to set
+ *      the XHR's withCredentials (for accessing secure data).
+ * @param {Number} [options.width]
  *      Width of the source image at max resolution in pixels.
- * @param {Number} tileSize
+ * @param {Number} [options.height]
+ *      Height of the source image at max resolution in pixels.
+ * @param {Number} [options.tileSize]
  *      The size of the tiles to assumed to make up each pyramid layer in pixels.
  *      Tile size determines the point at which the image pyramid must be
  *      divided into a matrix of smaller images.
- * @param {Number} tileOverlap
+ * @param {Number} [options.tileOverlap]
  *      The number of pixels each tile is expected to overlap touching tiles.
- * @param {Number} minLevel
+ * @param {Number} [options.minLevel]
  *      The minimum level to attempt to load.
- * @param {Number} maxLevel
+ * @param {Number} [options.maxLevel]
  *      The maximum level to attempt to load.
  */
 $.TileSource = function( width, height, tileSize, tileOverlap, minLevel, maxLevel ) {