I bought these for my son so we could have matching running "Jorts". I saw a few kids on Instagram wearing various BOA shorts, so I asked the about the sizing. For a 10 year old little boy, the Women's XSM seems to fit perfectly. I have over 12 pairs of BOA shorts, they are fantastic and their warranty is bomb proof. They are the only shorts I wear for running, regardless of temperature. I wear a Men's XL, but these were a Women's XSM.