Do I need to mail in copies of my W-2's with tax return?

I am filing by mail for the first time and I see that the instructions say to mail in your W-2 along with the return. I recently moved but had filled out the paperwork prior to moving and now I cannot locate my W-2, and am not sure how quickly my previous employers will get me a copy as they can be difficult to work with.

 

Am I required to send in my W-2 along with the return?