Tina -- I congratulate you on knowing how to edit a resource's availability in the Resource Availability section of the Resource Information dialog. Most people do not know that feature exists, nor how to use it. The information you are lacking, however, is that setting the end of a resource's availability to December 31, 2023 WILL NOT prevent PMs from assigning that resource to tasks after December 31, 2023. All that this will do is to show that the resource is overallocated if the resource is assigned to tasks AFTER that date. In fact, there is no feature in Microsoft Project that will prevent a PM from assigning a resource in any circumstance. Sorry, but hope this helps.