diff --git a/config/galaxy.ini.sample b/config/galaxy.ini.sample
index 814ef564443..f4a8d8f0172 100644
--- a/config/galaxy.ini.sample
+++ b/config/galaxy.ini.sample
@@ -786,6 +786,14 @@ use_interactive = True
 # public.
 #new_user_dataset_access_role_default_private = False
 
+# Expose user list. Setting this to true will expose the user list to authenticated users. This
+# makes sharing datasets in smaller galaxy instances much easier as they can type a name/email and
+# have the correct user show up. This makes less sense on large public galaxy instances where 
+# that data shouldn't be exposed. For semi-public galaxies, it may make sense to expose just the
+# username and not email, or vice versa.
+#expose_user_name = False
+#expose_user_email = False
+
 # -- Beta features
 
 # Use new tool form
diff --git a/lib/galaxy/config.py b/lib/galaxy/config.py
index 9103f0cc927..627b801f97f 100644
--- a/lib/galaxy/config.py
+++ b/lib/galaxy/config.py
@@ -106,6 +106,9 @@ class Configuration( object ):
         self.user_label_filters = listify( kwargs.get( "user_tool_label_filters", [] ), do_strip=True )
         self.user_section_filters = listify( kwargs.get( "user_tool_section_filters", [] ), do_strip=True )
 
+        self.expose_user_name = kwargs.get( "expose_user_name", False )
+        self.expose_user_email = kwargs.get( "expose_user_email", False )
+
         # Check for tools defined in the above non-shed tool configs (i.e., tool_conf.xml) tht have
         # been migrated from the Galaxy code distribution to the Tool Shed.
         self.check_migrate_tools = string_as_bool( kwargs.get( 'check_migrate_tools', True ) )
diff --git a/lib/galaxy/model/__init__.py b/lib/galaxy/model/__init__.py
index af23da816b7..cb1bc27687d 100644
--- a/lib/galaxy/model/__init__.py
+++ b/lib/galaxy/model/__init__.py
@@ -131,7 +131,7 @@ class User( object, Dictifiable ):
     histories, credentials, and roles.
     """
     # attributes that will be accessed and returned when calling to_dict( view='collection' )
-    dict_collection_visible_keys = ( 'id', 'email' )
+    dict_collection_visible_keys = ( 'id', 'email', 'username' )
     # attributes that will be accessed and returned when calling to_dict( view='element' )
     dict_element_visible_keys = ( 'id', 'email', 'username', 'total_disk_usage', 'nice_total_disk_usage' )
 
diff --git a/lib/galaxy/webapps/galaxy/api/users.py b/lib/galaxy/webapps/galaxy/api/users.py
index 6a3cea2be02..5b98b485b7f 100644
--- a/lib/galaxy/webapps/galaxy/api/users.py
+++ b/lib/galaxy/webapps/galaxy/api/users.py
@@ -43,11 +43,19 @@ class UserAPIController( BaseAPIController, UsesTagsMixin, CreatesUsersMixin, Cr
         else:
             query = query.filter( trans.app.model.User.table.c.deleted == False )  # noqa
             # special case: user can see only their own user
-            if not trans.user_is_admin():
+            # special case2: if the galaxy admin has specified that other user email/names are
+            #   exposed, we don't want special case #1
+            if not trans.user_is_admin() and not trans.app.config.expose_user_name and not trans.app.config.expose_user_email:
                 item = trans.user.to_dict( value_mapper={ 'id': trans.security.encode_id } )
                 return [item]
         for user in query:
             item = user.to_dict( value_mapper={ 'id': trans.security.encode_id } )
+            # If NOT configured to expose_email, do not expose email UNLESS the user is self, or
+            # the user is an admin
+            if not trans.app.config.expose_user_name and user is not trans.user and not trans.user_is_admin():
+                del item['username']
+            if not trans.app.config.expose_user_email and user is not trans.user and not trans.user_is_admin():
+                del item['email']
             # TODO: move into api_values
             rval.append( item )
         return rval
diff --git a/templates/webapps/galaxy/history/share.mako b/templates/webapps/galaxy/history/share.mako
index fc778cdf252..98fea0911ba 100644
--- a/templates/webapps/galaxy/history/share.mako
+++ b/templates/webapps/galaxy/history/share.mako
@@ -36,10 +36,10 @@
                 </div>
                 <div style="clear: both"></div>
                 <div class="form-row">
+                    <% existing_emails = ','.join([ d.user.email for d in history.users_shared_with ]) %>
                     <label>Galaxy user emails with which to share histories</label>
-                    <div style="float: left; width: 250px; margin-right: 10px;">
-                        <input type="text" name="email" value="${email}" size="40">
-                    </div>
+                    <input type="hidden" id="email_select" name="email" value="${ existing_emails }" style="float: left; width: 250px; margin-right: 10px;">
+                    </input>
                     <div class="toolParamHelp" style="clear: both;">
                         Enter a Galaxy user email address or a comma-separated list of addresses if sharing with multiple users
                     </div>
@@ -55,6 +55,94 @@
                     <input type="submit" name="share_button" value="Submit">
                 </div>
             </form>
+            <script type="text/javascript">
+            // stolen from templates/admin/impersonate.mako
+            /*  This should be ripped out and made generic at some point for the
+             *  various API bindings available, and once the API can filter list
+             *  queries (term, below) */
+
+            var user_id = "${trans.security.encode_id(trans.user.id)}";
+            var history_id = "${trans.security.encode_id( history.id )}";
+
+            function item_to_label(item){
+                var text = "";
+                if(typeof(item.username) === "string" && typeof(item.email) === "string"){
+                    text = item.username + " <" + item.email + ">";
+                }else if(typeof(item.username) === "string"){
+                    text = item.username;
+                }else{
+                    text = item.email;
+                }
+                return text;
+                //return "id:" + item.id + "|e:" + item.email + "|u:" + item.username;
+            }
+
+            $("#email_select").select2({
+                placeholder: "Select a user",
+                multiple: true,
+                initSelection: function(element, callback) {
+                    var data = [
+                    // Must be here to loop across the users that this has been shared with.
+                    %for i, association in enumerate( history.users_shared_with ):
+                        <% shared_with = association.user %>
+                        {
+                            email: "${ shared_with.email }",
+                            id: "${trans.security.encode_id(shared_with.id)}",
+                            text: item_to_label({"email": "${ shared_with.email }", "username": "${ shared_with.username }" })
+                        }, 
+                    %endfor
+                    ];
+                    callback(data);
+                },
+                tokenSeparators: [',', ' '],
+                // Required for initSelection
+                id: function(object) {
+                    return object.id;
+                },
+                ajax: {
+                    url: "${h.url_for(controller="/api/users", action="index")}",
+                    data: function (term) {
+                        return {
+                            f_email: term
+                        };
+                    },
+                    dataType: 'json',
+                    quietMillis: 250,
+                    results: function (data) {
+                        var results = [];
+                        // For every user returned by the API call,
+                        $.each(data, function(index, item){
+                            // If they aren't the requesting user, add to the
+                            // list that will populate the select
+                            if(item.id != "${trans.security.encode_id(trans.user.id)}"){
+                                results.push({
+                                  id: item.id,
+                                  name: item.username,
+                                  text: item_to_label(item),
+                                });
+                            }
+                        });
+                        return {
+                            results: results
+                        };
+                    }
+                },
+                createSearchChoice: function(term, data) {
+                    // Check for a user with a matching email.
+                    var matches = _.filter(data, function(user){
+                        return user.text.indexOf(term) > -1;
+                    });
+                    // If there aren't any users with matching object labels, then 
+                    // display a "default" entry with whatever text they're entering.
+                    // id is set to term as that will be used in 
+                    if(matches.length == 0){
+                        return {id: term, text:term};
+                    }else{
+                        // No extra needed
+                    }
+                }
+            });
+            </script>
         %else:
             ## We are sharing restricted histories
             %if no_change_needed or can_change: