It may be poly/cotton twill but it feels like all cotton in that it's very soft. It's comfortable without feeling overly lightweight. I needed a small and only small-longs were available, but all I need to do is adjust the sleeves a few inches. Having more torso room isn't terrible either because I can put a vest on and still have pocket access. Fits very well. Feels durable. I would definitely recommend - Propper delivers.