I love, love, love this t-shirt, but it runs really SMALL. Fortunately I read the other reviews before ordering. I normally wear a M but ordered an XL and it fits perfectly. If you like your shirts skin-tight, then order 1 size up. If you're busty or just like a little room, order 2 sizes up. The fabric is lightweight but not see-through, which is nice. Great for warm weather!