Eating disorders are among the most prevalent psychiatric disorders in adolescent and young adult females, affecting approximately 10% of young women. Unfortunately, less than half of those with eating disorders receive treatment, which can be very expensive. Thus, effective prevention has become a major public health priority. The Body Project is an empirically based eating disorder prevention program that offers young women an opportunity to critically consider the costs of pursuing the ultra-thin ideal promoted in the mass media, which improves body acceptance and reduces risk for developing eating disorders. Young women with elevated body dissatisfaction are recruited for group sessions in which they participate in a series of verbal, written, and behavioral exercises in which they consider the negative effects of pursuing the thin-ideal. Chapters provide information on the significance of body image and eating disorders, the intervention theory, the evidence base which supports the theory, recruitment and training procedures, solutions to common challenges, and a new program aimed at reducing obesity onset, as well as intervention scripts and participant handouts. The Body Project is the only currently available eating disorder prevention program that has been shown to reduce risk for onset of eating disorders and received support in trials conducted by several independent research groups. The group sessions are brief and fun to lead, and this guide provides all of the necessary information to walk clinicians, teachers, counselors, and volunteers through leading the program for vulnerable young women.