We go to the park a lot where there are tons of kids; but the kids there in general are pretty rude. Are they just that mean to everyone, or is it just him?
I really loved the book
Good Friends Are Hard to Find: Help Your Child Find, Make, and Keep Friends (Paperback)
~ Fred Frankel (Author), Barry Wetmore
when my son was this age. There are unwritten rules about how to join a group, and after reading this book, I could teach them to my son. Perhaps it won't work, but it seems like a logical place to start.
Best Wishes,
Grinity