I am 5'7 and 125 lbs. I ordered a small. This shirt is great. The color is rich and it's not really see-through or super tight. It's just long enough to wear with a cute late cami underneath for a little flare. And, the arms are actually a good length! I always have a hard time finding long enough arms on long sleeve t's. Plus, neck line is great too. Plan to order more colors.