A number of previous reviews discussed a size problem - believe it. I ordered a medium; too small. Kept it for my wife who liked the beret, and so I didn't need to go through the pain of returning it.
Ordered a large (next size up); too big. In both cases, I couldn't use the hat at all. So I bought, cut, and glued a strip of thick felt around the inner band. The large fits just right now - but I had to expend more money, time, and work.
You may be luckier. I suppose the hat fits some people off the bat. If it does, you'll be happy. It's a really nice beret: looks good, good quality, good shape.