diff --git a/src/base/collection.js b/src/base/collection.js
index a12bf872..398e614c 100644
--- a/src/base/collection.js
+++ b/src/base/collection.js
@@ -140,9 +140,9 @@ CollectionBase.prototype.toString = function() {
  * Override this function if you want to customize its output.
 *
  * @param {Object=} options
- * @param {bool}    [options.shallow=false]   Exclude relations.
- * @param {bool}    [options.omitPivot=false] Exclude pivot values.
- * @param {bool}    [options.omitNew=false]   Exclude models that return true for isNew.
+ * @param {Boolean}    [options.shallow=false]   Exclude relations.
+ * @param {Boolean}    [options.omitPivot=false] Exclude pivot values.
+ * @param {Boolean}    [options.omitNew=false]   Exclude models that return true for isNew.
  * @returns {Object} Serialized model as a plain object.
  */
 CollectionBase.prototype.serialize = function(options) {
diff --git a/src/base/model.js b/src/base/model.js
index a137e93f..a96bdbf7 100644
--- a/src/base/model.js
+++ b/src/base/model.js
@@ -129,13 +129,37 @@ ModelBase.prototype.initialize = function() {};
 ModelBase.prototype.idAttribute = 'id';
 
 /**
- * @member {boolean|Array}
+ * @member {Object|Null}
+ * @default null
+ * @description
+ *
+ * This can be used to define any default values for attributes that are not
+ * present when creating or updating a model in a {@link Model#save save} call.
+ * The default behavior is to *not* use these default values on updates unless
+ * the `defaults: true` option is passed to the {@link Model#save save} call.
+ * For inserts the default values will always be used if present.
+ *
+ * @example
+ *
+ * var MyModel = bookshelf.Model.extend({
+ *   defaults: {property1: 'foo', property2: 'bar'},
+ *   tableName: 'my_table'
+ * })
+ *
+ * MyModel.forge({property1: 'blah'}).save().then(function(model) {
+ *   // {property1: 'blah', property2: 'bar'}
+ * })
+ */
+ModelBase.prototype.defaults = null;
+
+/**
+ * @member {Boolean|Array}
  * @default false
  * @description
  *
  * Sets the current date/time on the timestamps columns `created_at` and
  * `updated_at` for a given method. The 'update' method will only update
- * `updated_at`.  To override the default column names, assign an array
+ * `updated_at`. To override the default column names, assign an array
  * to {@link Model#hasTimestamps hasTimestamps}.  The first element will
  * be the created column name and the second will be the updated
  * column name.
@@ -312,8 +336,8 @@ ModelBase.prototype.isNew = function() {
  * // {firstName: "Wassily", lastName: "Kandinsky", birthday: "December 16, 1866"}
  *
  * @param {Object=} options
- * @param {bool}    [options.shallow=false]   Exclude relations.
- * @param {bool}    [options.omitPivot=false] Exclude pivot values.
+ * @param {Boolean}    [options.shallow=false]   Exclude relations.
+ * @param {Boolean}    [options.omitPivot=false] Exclude pivot values.
  * @returns {Object} Serialized model as a plain object.
  */
 ModelBase.prototype.serialize = function(options = {}) {
@@ -385,7 +409,7 @@ ModelBase.prototype.escape = function(key) {
  * @description
  * Returns `true` if the attribute contains a value that is not null or undefined.
  * @param {string} attribute The attribute to check.
- * @returns {bool} True if `attribute` is set, otherwise `false`.
+ * @returns {Boolean} True if `attribute` is set, otherwise `false`.
  */
 ModelBase.prototype.has = function(attr) {
   return this.get(attr) != null;
@@ -619,7 +643,7 @@ ModelBase.prototype.timestamp = function(options) {
  * specific attribute has changed.
  *
  * @param {string=} attribute
- * @returns {bool}
+ * @returns {Boolean}
  * `true` if any attribute has changed. Or, if `attribute` was specified, true
  * if it has changed.
  */
diff --git a/src/bookshelf.js b/src/bookshelf.js
index 59dc8e99..61fc4374 100644
--- a/src/bookshelf.js
+++ b/src/bookshelf.js
@@ -57,11 +57,11 @@ function Bookshelf(knex) {
      * @param {Object=} attributes Initial values for this model's attributes.
      * @param {Object=}  options               Hash of options.
      * @param {string=}  options.tableName     Initial value for {@linkcode Model#tableName tableName}.
-     * @param {boolean=} [options.hasTimestamps=false]
+     * @param {Boolean=} [options.hasTimestamps=false]
      *
      *   Initial value for {@linkcode Model#hasTimestamps hasTimestamps}.
      *
-     * @param {boolean} [options.parse=false]
+     * @param {Boolean} [options.parse=false]
      *
      *   Convert attributes by {@linkcode Model#parse parse} before being
      *   {@linkcode Model#set set} on the `model`.
diff --git a/src/collection.js b/src/collection.js
index bbea2b64..4a602e3f 100644
--- a/src/collection.js
+++ b/src/collection.js
@@ -31,7 +31,7 @@ import createError from 'create-error';
  *
  * @param {(Model[])=} models Initial array of models.
  * @param {Object=} options
- * @param {bool} [options.comparator=false]
+ * @param {Boolean} [options.comparator=false]
  *   {@link Collection#comparator Comparator} for collection, or `false` to disable sorting.
  */
 const BookshelfCollection = CollectionBase.extend({
@@ -101,7 +101,7 @@ const BookshelfCollection = CollectionBase.extend({
    *   Upon a sucessful query resulting in no records returns. Only fired if `require: true` is passed as an option.
    *
    * @param {Object=} options
-   * @param {bool} [options.require=false] Trigger a {@link Collection.EmptyError} if no records are found.
+   * @param {Boolean} [options.require=false] Trigger a {@link Collection.EmptyError} if no records are found.
    * @param {string|string[]} [options.withRelated=[]] A relation, or list of relations, to be eager loaded as part of the `fetch` operation.
    * @returns {Promise<Collection>}
    */
@@ -209,7 +209,7 @@ const BookshelfCollection = CollectionBase.extend({
    *   });
    *
    * @param {Object=}  options
-   * @param {boolean} [options.require=false]
+   * @param {Boolean} [options.require=false]
    *   If `true`, will reject the returned response with a {@link
    *   Model.NotFoundError NotFoundError} if no result is found.
    * @param {(string|string[])} [options.columns='*']
diff --git a/src/model.js b/src/model.js
index c374d7d4..d7f32ea0 100644
--- a/src/model.js
+++ b/src/model.js
@@ -50,11 +50,11 @@ import Promise from './base/promise';
  * @param {Object}   attributes            Initial values for this model's attributes.
  * @param {Object=}  options               Hash of options.
  * @param {string=}  options.tableName     Initial value for {@link Model#tableName tableName}.
- * @param {boolean=} [options.hasTimestamps=false]
+ * @param {Boolean=} [options.hasTimestamps=false]
  *
  *   Initial value for {@link Model#hasTimestamps hasTimestamps}.
  *
- * @param {boolean} [options.parse=false]
+ * @param {Boolean} [options.parse=false]
  *
  *   Convert attributes by {@link Model#parse parse} before being {@link
  *   Model#set set} on the model.
@@ -650,7 +650,7 @@ const BookshelfModel = ModelBase.extend({
    * @method Model#fetch
    *
    * @param {Object=}  options - Hash of options.
-   * @param {boolean=} [options.require=false]
+   * @param {Boolean=} [options.require=false]
    *   Reject the returned response with a {@link Model.NotFoundError
    *   NotFoundError} if results are empty.
    * @param {string|string[]} [options.columns='*']
@@ -779,7 +779,7 @@ const BookshelfModel = ModelBase.extend({
    * @method Model#fetchAll
    *
    * @param {Object=}  options - Hash of options.
-   * @param {boolean=} [options.require=false]
+   * @param {Boolean=} [options.require=false]
    *
    *  Rejects the returned promise with an `Collection.EmptyError` if no records are returned.
    *
@@ -873,22 +873,31 @@ const BookshelfModel = ModelBase.extend({
    * @method Model#save
    * @description
    *
-   * `save` is used to perform either an insert or update query using the
+   * This method is used to perform either an insert or update query using the
    * model's set {@link Model#attributes attributes}.
    *
    * If the model {@link Model#isNew isNew}, any {@link Model#defaults defaults}
    * will be set and an `insert` query will be performed. Otherwise it will
-   * `update` the record with a corresponding ID. This behaviour can be overriden
-   * with the `method` option.
-   *
-   *     new Post({name: 'New Article'}).save().then(function(model) {
-   *       // ...
-   *     });
+   * `update` the record with a corresponding ID. It is also possible to
+   * set default attributes on an `update` by passing the `{defaults: true}`
+   * option in the second argument to the `save` call. This will also use the
+   * same {@link Model#defaults defaults} as the `insert` operation.
+   *
+   * The type of operation to perform (either `insert` or `update`) can be
+   * overriden with the `method` option:
+   *
+   *     // This forces an insert with the specified id instead of the expected
+   *     // update
+   *     new Post({name: 'New Article', id: 34})
+   *       .save(null, {method: 'insert'})
+   *       .then(function(model) {
+   *         // ...
+   *       });
    *
    * If you only wish to update with the params passed to the save, you may pass
-   * a {patch: true} flag to the database:
+   * a `{patch: true}` option in the second argument to `save`:
    *
-   *     // update authors set "bio" = 'Short user bio' where "id" = 1
+   *     // UPDATE authors SET "bio" = 'Short user bio' WHERE "id" = 1
    *     new Author({id: 1, first_name: 'User'})
    *       .save({bio: 'Short user bio'}, {patch: true})
    *       .then(function(model) {
@@ -907,13 +916,19 @@ const BookshelfModel = ModelBase.extend({
    * available in `options.query`.
    *
    *     // Save with no arguments
-   *     Model.forge({id: 5, firstName: "John", lastName: "Smith"}).save().then(function() { //...
+   *     Model.forge({id: 5, firstName: 'John', lastName: 'Smith'}).save().then(function() {
+   *       //...
+   *     });
    *
    *     // Or add attributes during save
-   *     Model.forge({id: 5}).save({firstName: "John", lastName: "Smith"}).then(function() { //...
+   *     Model.forge({id: 5}).save({firstName: 'John', lastName: 'Smith'}).then(function() {
+   *       //...
+   *     });
    *
    *     // Or, if you prefer, for a single attribute
-   *     Model.forge({id: 5}).save('name', 'John Smith').then(function() { //...
+   *     Model.forge({id: 5}).save('name', 'John Smith').then(function() {
+   *       //...
+   *     });
    *
    * @param {string=}      key                      Attribute name.
    * @param {string=}      val                      Attribute value.
@@ -923,11 +938,12 @@ const BookshelfModel = ModelBase.extend({
    *   Optionally run the query in a transaction.
    * @param {string=} options.method
    *   Explicitly select a save method, either `"update"` or `"insert"`.
-   * @param {string} [options.defaults=false]
-   *   Assign {@link Model#defaults defaults} in an `update` operation.
-   * @param {bool} [options.patch=false]
+   * @param {Boolean} [options.defaults=false]
+   *   Whether to assign or not {@link Model#defaults default} attribute values
+   *   on a model when performing an update or create operation.
+   * @param {Boolean} [options.patch=false]
    *   Only save attributes supplied in arguments to `save`.
-   * @param {bool} [options.require=true]
+   * @param {Boolean} [options.require=true]
    *   Throw a {@link Model.NoRowsUpdatedError} if no records are affected by save.
    *
    * @fires Model#saving
@@ -1150,7 +1166,7 @@ const BookshelfModel = ModelBase.extend({
    *
    * @param {Object=}      options                  Hash of options.
    * @param {Transaction=} options.transacting      Optionally run the query in a transaction.
-   * @param {bool} [options.require=true]
+   * @param {Boolean} [options.require=true]
    *   Throw a {@link Model.NoRowsDeletedError} if no records are affected by destroy. This is
    *   the default behavior as of version 0.13.0.
    *
diff --git a/src/relation.js b/src/relation.js
index 8d55d268..3d8e78bd 100644
--- a/src/relation.js
+++ b/src/relation.js
@@ -605,7 +605,7 @@ const pivotHelpers = {
    * @param {function|Object} [options.query]
    *   Constrain the update query. Similar to the `method` argument to {@link
    *   Model#query}.
-   * @param {bool} [options.require=false]
+   * @param {Boolean} [options.require=false]
    *   Causes promise to be rejected with an Error if no rows were updated.
    * @param {Transaction} [options.transacting]
    *   Optionally run the query in a transaction.