This book by Madonna is a hit with my fourth and fifth grade female students.  The main characters are five girls who appear to be approximately 11 or 12 years old.  The setting is England and in this book, two travel to the United States.  The book is sophisticated in geographical sense and socially, but not offensive or inappropriate by any measure.  The five girls in this tight friendship circle are Amy, Binah, Grace, Nicole, and Charlotte.  What is sophisticated about them is how well they treat each other.  Their loyalty and consideration of each other is a model for girls struggling in their friendships.  Well written, students like it, and I like the subtle message of friendship and the international flavor.