Whenever ordering clothes online for the first time, I never know how they will fit. In this case, I ordered an XL and I actually like how roomy it was. I'm 5"3/175lbs (mostly muscle) and 36DD (for reference purposes)and I can (usually) wear a Large and be fine. That being said, working in the construction industry, my shoulders and arms are big so trying to fit into some normal women's/juniors shirts can be a challenge at times. If you normally wear a Large, I feel the shirt should be fine but ...