you will receive as many *opinions* on this as there are people...it is up to you- it will not make a huge difference in the long run what you decide to do- there are people who believe they have to pre-wash every single thing (even their batting) and there are those who pre-wash nothing---then there are those of us who pre-wash what we think needs it & don't worry about the rest---mixing both in a project...everyone makes successful beautiful quilts- regardless of which *school* they belong to. me, I pre-wash if I think it may bleed, if it smells funky or feels funky, or if it has a loose weave I am hoping to tighten up- other than that...pretty much every quilt I've ever made contains both washed & unwashed fabrics...one thing though---if I purchase *used* fabric from any source other than a regular store---yard sales, thrift stores, ebay, anywhere it has been in someone's home---even if it seems like it's been washed---I pre-wash it! you never know what you may bring in when it's come from a *private setting* if I purchase any fabric from anywhere like that it does not even go to my sewing room- or main part of house- it comes in from the garage & stops at the washer.