I agree with other reviewers, that you need to try this on in a running store first. I am a 34F and I am able to wear a 34DD Fiona. This is the only sports bra I've bought over the last 4 years. Once I actually found a bra that I could run in I stuck with it. I'd done it all over the years--multiple bras, wrapping, etc. Nothing worked. Was super uncomfortable. Still had bounce. Ugh.

One suggestion that I was given at my local running store was a good sports bra isn't too tight, but you're not able to hook it in the back...instead you hook in the front and "granny" it into position. Once they stretch enough where you can easily hook it behind your back it's time for a new one. Not sure how true this advice is, but once I am able to get it hooked in the back and I try on a new one the support and elastic is way better ;)