Karen's Pony Camp (Baby-Sitters Little Sister series) by Ann M. Martin

Karen is a little girl that is seven and is in second grade she has two families and she lives with her mom and step-dad and she visits her father every other weekend her dad has a mansion and her mom has a small house she is going to a pony camp with her best friends Hannie and Nancy she is sooo exited about it but when she gets there she has to pick out a horse she picks out a palomino Diablo he is just beautiful but after a while older kids make fun of her and Nancy is afraid of riding Hannie rides too much they aren't having much fun.

What I like about the story is that it has ponies in it and horses and I am all over ponies and horses and if there is a book with animals especially when it's with horses or ponies.