I guess I was so convinced by the look of these in the photo that I didn't pay attention to the reviews describing them as "t-shirt" material.  The "100% cotton" should have also clued me in -- it's been decades since I've seen real sweatpants in 100% cotton.  These are thin jersey, not any sort of fleece-backed jersey or french terry typical for sweatpants.  Suitable for summer if you need long pants to protect yourself against mosquitoes & ticks, maybe.