diff --git a/polymer-micro.html b/polymer-micro.html
index cbc4f0c5c3..3cfa935ef8 100644
--- a/polymer-micro.html
+++ b/polymer-micro.html
@@ -23,6 +23,8 @@
     _registerFeatures: function() {
       // identity
       this._prepIs();
+      // attributes
+      this._prepAttributes();
       // shared behaviors
       this._prepBehaviors();
       // inheritance
@@ -31,18 +33,20 @@
       this._prepConstructor();
     },
 
-    _prepBehavior: function() {},
+    _prepBehavior: function(b) {
+      this._addHostAttributes(b.hostAttributes);
+    },
+
+    _marshalBehavior: function(b) {
+    },
 
     _initFeatures: function() {
+      // install host attributes
+      this._marshalHostAttributes();
       // setup debouncers
       this._setupDebouncers();
       // acquire behaviors
       this._marshalBehaviors();
-    },
-
-    _marshalBehavior: function(b) {
-      // publish attributes to instance
-      this._installHostAttributes(b.hostAttributes);
     }
 
   });
diff --git a/polymer-mini.html b/polymer-mini.html
index 389bc3c7c8..8290035cb1 100644
--- a/polymer-mini.html
+++ b/polymer-mini.html
@@ -24,6 +24,8 @@
     _registerFeatures: function() {
       // identity
       this._prepIs();
+      // attributes
+      this._prepAttributes();
       // shared behaviors
       this._prepBehaviors();
       // inheritance
@@ -36,7 +38,9 @@
       this._prepShady();
     },
 
-    _prepBehavior: function() {},
+    _prepBehavior: function(b) {
+      this._addHostAttributes(b.hostAttributes);
+    },
 
     _initFeatures: function() {
       // manage local dom
@@ -47,6 +51,8 @@
       this._stampTemplate();
       // host stack
       this._popHost();
+      // install host attributes
+      this._marshalHostAttributes();
       // setup debouncers
       this._setupDebouncers();
       // instance shared behaviors
@@ -56,8 +62,6 @@
     },
 
     _marshalBehavior: function(b) {
-      // publish attributes to instance
-      this._installHostAttributes(b.hostAttributes);
     }
 
   });
diff --git a/polymer.html b/polymer.html
index bc5517c396..916c9ff6b5 100644
--- a/polymer.html
+++ b/polymer.html
@@ -28,6 +28,8 @@
     _registerFeatures: function() {
       // identity
       this._prepIs();
+      // attributes
+      this._prepAttributes();
       // inheritance
       this._prepExtends();
       // factory
@@ -51,8 +53,9 @@
     },
 
     _prepBehavior: function(b) {
-      this._addPropertyEffects(b.properties || b.accessors);
+      this._addPropertyEffects(b.properties);
       this._addComplexObserverEffects(b.observers);
+      this._addHostAttributes(b.hostAttributes);
     },
 
     _initFeatures: function() {
@@ -70,6 +73,8 @@
       this._popHost();
       // concretize template references
       this._marshalAnnotationReferences();
+      // install host attributes
+      this._marshalHostAttributes();
       // setup debouncers
       this._setupDebouncers();
       // concretize effects on instance
@@ -83,8 +88,6 @@
     },
 
     _marshalBehavior: function(b) {
-      // publish attributes to instance
-      this._installHostAttributes(b.hostAttributes);
       // establish listeners on instance
       this._listenListeners(b.listeners);
     }
diff --git a/src/micro/attributes.html b/src/micro/attributes.html
index 62b97247da..564ff42634 100644
--- a/src/micro/attributes.html
+++ b/src/micro/attributes.html
@@ -60,21 +60,25 @@
 
   Polymer.Base._addFeature({
 
-    _marshalAttributes: function() {
-      this._takeAttributes();
+    _prepAttributes: function() {
+      this._aggregatedAttributes = {};
     },
 
-    _installHostAttributes: function(attributes) {
+    _addHostAttributes: function(attributes) {
       if (attributes) {
-        this._applyAttributes(this, attributes);
+        this.mixin(this._aggregatedAttributes, attributes);
       }
     },
 
+    _marshalHostAttributes: function() {
+      this._applyAttributes(this, this._aggregatedAttributes);
+    },
+
     /* apply attributes to node but avoid overriding existing values */
     _applyAttributes: function(node, attr$) {
       for (var n in attr$) {
         // NOTE: never allow 'class' to be set in hostAttributes
-        // since shimming classes would make it work 
+        // since shimming classes would make it work
         // inconsisently under native SD
         if (!this.hasAttribute(n) && (n !== 'class')) {
           this.serializeValueToAttribute(attr$[n], n, this);
@@ -82,7 +86,7 @@
       }
     },
 
-    _takeAttributes: function() {
+    _marshalAttributes: function() {
       this._takeAttributesToModel(this);
     },
 
@@ -106,6 +110,7 @@
     },
 
     _serializing: false,
+
     reflectPropertyToAttribute: function(name) {
       this._serializing = true;
       this.serializeValueToAttribute(this[name],
diff --git a/src/micro/behaviors.html b/src/micro/behaviors.html
index c3420ff47a..443863e309 100644
--- a/src/micro/behaviors.html
+++ b/src/micro/behaviors.html
@@ -46,7 +46,7 @@
       if (this.behaviors.length) {
         this.behaviors = this._flattenBehaviorsList(this.behaviors);
       }
-      this._prepAllBehaviors();
+      this._prepAllBehaviors(this.behaviors);
     },
 
     _flattenBehaviorsList: function(behaviors) {
@@ -54,35 +54,41 @@
       behaviors.forEach(function(b) {
         if (b instanceof Array) {
           flat = flat.concat(this._flattenBehaviorsList(b));
-        } else {
+        }
+        // filter out null entries so other iterators don't need to check
+        else if (b) {
           flat.push(b);
+        } else {
+          this._warn(this._logf('_flattenBehaviorsList', 'behavior is null, check for missing or 404 import'));
         }
       }, this);
       return flat;
     },
 
-    _prepAllBehaviors: function() {
-      // filter so other iterators don't need null check
-      this.behaviors = this.behaviors.filter(function(b) {
-        if (b) {
-          this._mixinBehavior(b);
-          this._prepBehavior(b);
-          return true;
-        }
-        this._warn(this._logf('_prepAllBehaviors', 'behavior is null, check for missing or 404 import'));
-      }, this);
+    _prepAllBehaviors: function(behaviors) {
+      // traverse the behaviors in _reverse_ order (youngest first) because
+      // `_mixinBehavior` has _first property wins_ behavior, this is done
+      // to optimize # of calls to `_copyOwnProperty`
+      for (var i=behaviors.length-1; i>=0; i--) {
+        this._mixinBehavior(behaviors[i]);
+      }
+      // we iterate a second time so that `_prepBehavior` goes in natural order
+      // otherwise, it's a tricky detail for implementors of `_prepBehavior`
+      for (var i=0, l=behaviors.length; i<l; i++) {
+        this._prepBehavior(behaviors[i]);
+      }
+      // prep our prototype-as-behavior
       this._prepBehavior(this);
     },
 
     _mixinBehavior: function(b) {
-      Object.getOwnPropertyNames(b).forEach(function(n) {
+       Object.getOwnPropertyNames(b).forEach(function(n) {
         switch (n) {
+          case 'hostAttributes':
           case 'registered':
           case 'properties':
           case 'observers':
           case 'listeners':
-          case 'keyPresses':
-          case 'hostAttributes':
           case 'created':
           case 'attached':
           case 'detached':
diff --git a/src/micro/mixins.html b/src/micro/mixins.html
deleted file mode 100644
index 4f0b27462a..0000000000
--- a/src/micro/mixins.html
+++ /dev/null
@@ -1,40 +0,0 @@
-<!--
-@license
-Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
-This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
-The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
-Code distributed by Google as part of the polymer project is also
-subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
--->
-<script>
-
-  /**
-   * Automatically extend using objects referenced in `mixins` array. 
-   * 
-   *     Polymer({
-   *     
-   *       mixins: [
-   *         someMixinObject
-   *       ]
-   *     
-   *       ...
-   *     
-   *     });
-   * 
-   * @class base feature: mixins
-   */
-
-  Polymer.Base._addFeature({
-
-    _prepMixins: function() {
-      if (this.mixins) {
-        this.mixins.forEach(function(m) {
-          Polymer.Base.extend(this, m);
-        }, this);
-      }
-    }
-
-  });
-
-</script>
diff --git a/test/unit/behaviors-elements.html b/test/unit/behaviors-elements.html
index d186c4d7ec..6e99d45780 100644
--- a/test/unit/behaviors-elements.html
+++ b/test/unit/behaviors-elements.html
@@ -28,10 +28,20 @@
         value: false
       },
 
+      overridablePropertyB: {
+        value: false
+      },
+
       hasBehaviorA: {
         value: true
       }
+    },
+
+    _simpleProperty: 'A',
 
+    hostAttributes: {
+      behavior: 'A',
+      user: 'A'
     },
 
     listeners: {
@@ -76,10 +86,21 @@
 
       hasBehaviorB: {
         value: true
-      }
+      },
+
+      overridablePropertyB: {
+        value: true
+      },
 
     },
 
+    hostAttributes: {
+      behavior: 'B',
+      user: 'B'
+    },
+
+    _simpleProperty: 'B',
+
     _disabledChanged: function(disabled) {
       this.__disabled = disabled
     },
@@ -118,6 +139,7 @@
 
       behaviors: [
         Polymer.BehaviorA,
+        null,
         Polymer.BehaviorB
       ],
 
@@ -158,7 +180,9 @@
         value: true
       }
 
-    }
+    },
+
+    _simpleProperty: 'C'
 
   };
 
@@ -170,7 +194,9 @@
         value: true
       }
 
-    }
+    },
+
+    _simpleProperty: 'D'
 
   };
 
diff --git a/test/unit/behaviors.html b/test/unit/behaviors.html
index 9e45423334..54b1b1116d 100644
--- a/test/unit/behaviors.html
+++ b/test/unit/behaviors.html
@@ -59,7 +59,9 @@
   var el;
 
   setup(function() {
-    el = document.createElement('multi-behaviors');
+    var div = document.createElement('div');
+    div.innerHTML = '<multi-behaviors user="user"></multi-behaviors>';
+    el = div.firstElementChild;
     document.body.appendChild(el);
   });
 
@@ -103,14 +105,21 @@
     assert.equal(typeof el._setHasOptionsB, 'function');
   });
 
-  test('behavior overrides are last', function() {
-    assert.equal(el._toOverride, Polymer._toOverride, 'Behavior method was not overridden');
-    assert(el.overridableProperty, 'Behavior property was not overridden');
+  test('multi-behavior overrides ordering', function() {
+    assert.equal(el._toOverride, Polymer._toOverride, 'Behavior method was not overridden by prototype');
+    assert(el.overridableProperty, 'Behavior property was not overridden by prototype');
+    assert(el.overridablePropertyB, 'Behavior config-property was not overridden by sub-behavior');
   });
+
+  test('hostAttributes ordering', function() {
+    assert.equal(el.attributes.behavior.value, 'B', 'Behavior hostAttribute not overridden by subclass');
+    assert.equal(el.attributes.user.value, 'user', 'Behavior hostAttribute overrode user attribute');
+  });
+
 });
 
 
-suite('nexted-behaviors element', function() {
+suite('nested-behaviors element', function() {
 
   var el;
 
@@ -123,11 +132,12 @@
     document.body.removeChild(el);
   });
 
-  test('properties from nested behaviors', function() {
+  test('nested-behavior overrides ordering', function() {
     assert.ok(el.hasBehaviorA, "missing BehaviorA");
     assert.ok(el.hasBehaviorB, "missing BehaviorB");
     assert.ok(el.hasBehaviorC, "missing BehaviorC");
     assert.ok(el.hasBehaviorD, "missing BehaviorD");
+    assert.equal(el._simpleProperty, 'D', 'Behavior simple property was not overridden by sub-behavior');
   });
 
 });