At least the Granite Heather isn't - it's 60/40. Now that I think of it, a lot of shirts that color are a cotton/poly blend.

After reading the reviews on how large these are, but assuming that it was 100% cotton and would shrink, I bought my regular size - XL - tried it on when it arrived and it fit like a tent. I didn't find out it was a cotton blend until I took it out of the dryer and realized that it didn't shrink much at all, if any. I guess I'll just save it until I go camping - get it? tent > camping?

The shirt is very good quality and superior to other long sleeve tees I have purchased. Other than the first one being too big, I liked it so much I ordered another one in large, which should be a good fit.

I guess the black, white, navy, etc are all 100% cotton, but if you are thinking about the granite heather (great color by the way) be aware that it is 60% cotton and 40% polyester.