Stone, Mary Hanlon. Invisible Girl.
Stephanie lives in Boston with her alcoholic, abusive mother and her passive, ineffective father. After a particularly brutal beating, Stephanie's mother leaves the family. It is decided that Stephanie should go live with family friends out in California. The difficult part? The family is very wealthy, and the daughter, Annie, who is Stephanie's age hangs out with a group of friends that are right out of The Clique. The arrival of the beautiful and exotic Amal threatens Annie-- the boys like her better, so Annie and her friends feel a need to torture her. Stephanie is also not treated well, so she and Amal become friends. There are some very nice multicultural moments (Amal's family is Egyptian and Muslim), and Stephanie takes great comfort in Amal's mother, who is so different from her own.
This was a very good twist on the novels lately that concentrate on privileged students in private schools, who wear designer clothes. Stephanie's difficulties in fitting in and dealing with her situation are achingly realistic. Picky Reader will love this one, as will many students who are torn between problem novels and books about wealthy families.
Sorry no cover-- I'm on a netbook again because the wiring for the computers in the library is not completely done. Carpet is also supposed to arrive today. Students arrive tomorrow, and I will see all 200 and some 6th graders!