I'm 5'11", 172lb with a lean athletic build and 32" waist. I took a chance on ordering a medium and found it to be too small. I know it supposed to be form-fitting, but I felt somewhat like a superhero wearing spandex. After that fantasy faded, I could only imagine how this thing would have looked after shrinking in the wash. Also, I like my shirt collars to fit closer to the base of my neck(I'm 15.5") and this one was loose enough that I don't think even shrinkage in the wash would have brought it to where I'd like it. I've also noticed that some of these manufacturers feel the need to incorporate little, patriotic, red, white and blue elements in some of their clothes. It's very cheesy guys, stop it. Just stop.