I tried this on in-store, in both xs and small. I typically wear an xs, but thought given that it's fitted, I should probably size up, as I usually do in fitted tops. Both the xs and small fit very similarly and looked about the same on. Ultimately I ended up liking the feel of the xs on me bett...er, as I felt like the small was looser, specifically under the arm of the sleeveless side. (34A bra size could also be a factor). If your typically an xs and have a larger bra size, sizing up might be better. Though I adored the tank, I wasn't sure that I'd have anywhere to wear it and couldn't decide in which color to buy, since I didn't have a particular pair of pants on mind - I ended up leaving the store without buying any of them. I immediately regretted not buying - jumped online and bought 3 of them. They look absolutely beautiful paired with wide leg linen pants. I have an upcoming vacation and although I was already packed - couldn't resist adding these to my suitcase.