The Disreputable History of Frankie Landau-Banks by E. Lockhart
This book is about a teenage girl named Frankie who goes to school at Alabaster. When she begins dating Matthew Livingston, she starts to notice that he's always "hanging out with the guys." This makes her suspicious, so she follows him. This is how she discovers that he is a member of The Loyal Order of the Basset Hounds. I highly recommend this book. I really enjoyed reading about how Frankie, a girl, was able to be the mastermind behind an all-male society.