If you are managing multiple Team Foundation Server (TFS) project teams then you probably would prefer to filter the user/people selector based on project or roles. The standard list includes all users, which contains more users than necessary.

Visual Studio provides an option to modify the work item templates. You can access this option at Tools-Process Editor-Work Item Types-Open WIT From Server. Select the Team Foundation Server and Project Collection before clicking Connect. The available work item templates will appear. Next, select the appropriate template to apply the filter. In this example, the User Story was selected.

 On the Fields tab, select the Assigned To field.

After selecting the field, the Fields Definition will be presented.

Click the Rules tab, which provides the filtering options for the Assigned To field.

Select ALLOWEDVALUES and click Edit. You can assign a project group with the [project] placeholder and the name. In my case, assigning the TFS project team.

Once you save the work item template, visiting a User Story and selecting the Assigned To field will display the filtered user list.

You can also export the work item template and add to TFS source control. In this case, modifying the following XML will also update the filter.

 XML |  copy code |? 
<FieldDefinition name="Assigned To" refname="System.AssignedTo" type="String" syncnamechanges="true" reportable="dimension">
  <ALLOWEDVALUES expanditems="true" filteritems="excludegroups">
    <LISTITEM value="[project]\My Team" />
  <HELPTEXT>The person currently working on this story</HELPTEXT>

Hopefully, this tip can save you time applying a filter to a user/people selector.