I'm v grateful to those reviewers who warned me about the size.  My daughter is petite and 2.5 years old.  The 3T-4T size fit her well..and when I put a polo neck under it to keep her warm, the shoulder straps became a little tight and didn't want to sit on her shoulders (no big problem though).  She really liked it, so that was great!! And I was glad that I hadn't had to spend on a lot on something she won't wear much.  So yes, it does run very small.  As long as you know that, it's fine.  Oh, the antenna thing wasn't comfortable on her head by the way.