<p>The pre-application to Washington University in St. Louis is the supplement to the Common Application. Other than the pre-application, there is no supplement to the Common Application. In the Common Application website, when you hit “supplement” for WashU, you will be linked to the Pre-Application. Therefore, it is safe to say that the Pre-Application is WashU’s supplement to the common application. Some schools have pre-applications and supplements. WashU does not.</p>