I'm rather new to quilting. The first 2 I made I did not prewash the fabric. I really like the crispness of the fabric while I'm working with it. BUT, then this bedbug thing started and the quilt I'm working on now I order the fabric online from Hancock Fabric so I did prewash. It shrunk more than I though it would. I still had enough fabric but I wasn't expecting as much shrinkage. It was rather inexpensive fabric, not sure if this was a factor or not.