Eating disorders affect 12-25% of college women. Previous research established a positive correlation between sorority membership and eating disorders. We investigate a possible causal link between sororities and weight-related behaviors and eating disorders using data from the American College Health Association. Using Propensity Score Matching and Instrumental Variable methods, we confirm that sororities exert a negative effect on the weight-related behaviors of their members. However, females who are more resilient to these outcomes self-select into sororities, implying that females in sororities are less adversely affected by them than a female who was randomly selected to join a sorority would be.