I'll start by saying... I can usually size down in everything Athleta. Leggings I typically wear an XS or S but consistently wear an XXS or XS in Athleta. Tanks I almost always wear a M (sometimes even a L to accommodate my broad gymnast shoulders) but almost always size down to a S in Athleta (minu...s the Elation Crop, where I wear my true size M). I wear a size 34D bra, but based on reviews, decided to give size M A-C a shot, and so glad I did! The cups are snug but supportive without being overly so, and the straps accommodate my wide lats just fine. I definitely would not have been able to wear a size down in this bra as it would have pulled too much in the straps and probably cut off in the cups. I love the style of this one, simple but elegant with the one criss-crossed strap. I think I will get a lot of use out of this one running, weightlifting, and climbing!