If you do a search, you will come up with many many many discussions about this.

It comes down to:

some do

some don't

if you choose to pre-wash ...
wash (like colors) together ((separate lights from darks))
use a mild detergent-
do not use fabric softener
regular setting is fine
tumble dry in dryer - or line dry

reasons for pre-washing---
1. to check for color fastness...hate those running colors that ruin beautiful quilts.
2. to pre-shrink the fabrics so when your quilt is finished and washed the fabrics will behave (together)
3. to remove chemicals/oils/odors/soil from the fabric

some people do
some people don't
some people wish they had

personally-
if the fabric (might) bleed
if the fabric feels or smells funky or stiff
if i am mixing fabrics (flannels w/ flat cottons w/ corduroy...ect.
if i purchased it at a (big-box store-like joannes, wallyworld,hobby lobby ect)
if i purchased it from a thrift shop or yard sale.

and i wash and dry EVERY QUILT - as soon as the binding is finished...i want to see how it comes out before anyone else sees it...just in case....

I'm just starting a new quilt. 10 fabrics, 8 from Connecting Threads, 1 from LQS and 1 recycled shirt (it was the right color!). I washed & dried everything. I measured everything before I started. The CT fabric was the same size both before & after (so was the shirt ;-) ) The LQS fabric however, shrunk 1" per yard length wise and almost 1 1/2" width wise!! If I had just pieced it, with the LQS fabric shrinking at a different rate, the whole quilt top would have been distorted, especially since it made up about half the quilt pattern in this case.

:thumbup: :thumbup: for the measuring before and
after washing!

Nope! I personally find it easier to work with before it's been washed. I wash my quilts after they're completed on cold and no detergent either...why start the fading process before you have to? :shock:

I always prewash. Too afraid of bleeding and shrinkage. My mom and gram would be disappointed if I didn't :) and they are no longer with us. But somehow they would let me know!!

ditto big time!

You will find people pretty evenly divided. I don't prewash. Not even batiks, and I've never had a problem. So, it is entirely up to you. If you want to wash, and dry, and iron, and starch and iron some more before you cut and sew, go for it. I don't have the time, energy or inclination. Unless you have terrible allergies to new fabric, there is no need to do so. You'll have people tell you horror stories of "my fabric ran and ruined my whole quilt", but that can be avoided by washing in cool or lukewarm water, making sure the washing maching fill is set on super, and throwing a couple of color-catchers in.

I wash all fabric

ditto