Another one by E. Lockhart

The Disreputable History of Frankie Landau-Banks, by E. Lockhart, tells the story of geek-turned-beauty Frankie as she traverses her sophomore year at an exclusive (is there any other kind?) East Coast prep school. She's getting noticed now that she's curvaceous and lands a hot senior boyfriend on her first day back on campus, but she has qualms about the whole beauty v. substance dichotomy that the school seems to nurture. The plot thickens when she figures out that her beau belongs to the school's infamous secret society, the very one her father had been in oh-so-many-years-ago. Of course it's only for boys, yet Frankie not only locates the long-lost club history, but also figures out a way to trick the boys into doing her bidding in a series of amazing pranks by impersonating the co-president of the club through an ambiguous email address. He's the "alpha" dog of the pack and ignores her as much as possible. Her fabulous boyfriend never confides in her about the pranks or the secret club and Frankie grows increasingly dissatisfied with their relationship and the "Old Boy" patriarchy rampant at the school.

Yes, it's all fairly predictable, but Lockhart throws in some interesting Foucauldian theory about institutions (the Panopticon!), and Frankie herself is an endearing character coping with normal teen issues. Great read for teen girls. Very mild sexual content.