Don't Judge a Girl by Her Cover is a 2009 young adult novel written by Ally Carter.

It is the sequel to Cross My Heart and Hope to Spy and the third book in the Gallagher Girls series.

The book spent three weeks, from June 19, 2009, to July 3, 2009[5] on the Children's Books version of The New York Times Best Seller list, debuting at #6.

[6] The main character Cammie joins Liz and Bex as Macey's private security team on the campaign trail.

The girls use their spy training at every turn as the stakes are raised, and Cammie discovers an "the unexpected truth", that she is the target of a secret society.