This leotard is adorable and very nicely made. My daughter is squeezing into the L because I can't return it for a bigger size -- loves it THAT much! She is a very thin 10-12, so I ordered the L (12-14). It fits more like a tiny 8-10.
I bought this leotard for my 45-pound 7 year old. She wears a size 6 in street clothes. Based on her measurements I ordered this leotard in the Child Intermediate (6x-7) size and it is TINY, more like a size 4-5. I'm returning it for the Medium 8-10 size. It's a very cute leotard, though, nice fabric and appears to be well-made. As a side note: for anyone who orders the matching booty shorts, those run true to size.