Gender role norms may play a crucial role in the male experience of eating disorders. The masculinity hypothesis proposes that conformity to masculine gender roles including dominance, confidence, sexual success, and physical and emotional self-control places men at risk for muscularity-oriented body dissatisfaction and disordered eating. However, despite some empirical support for this hypothesis, several gaps in the literature remain. The present study was the first to use multidimensional instruments of gender role conformity to investigate whether masculinity and femininity are associated with male body dissatisfaction and disordered eating. Participants were 246 young heterosexual men who completed an online survey that asked questions about muscle dissatisfaction, body fat dissatisfaction, thinness- and muscularity-oriented disordered eating. Results from 4 simultaneous multiple regressions showed that increased conformity to masculine norms predicted greater muscle dissatisfaction and muscularity-oriented disordered eating, but not body fat dissatisfaction or thinness-oriented disordered eating. Conformity to feminine norms predicted greater muscle dissatisfaction, thinness- and muscularity-oriented disordered eating. The results provide support for the masculinity hypothesis and extend it to include muscularity-oriented disordered eating. Furthermore, the results suggest that the femininity hypothesis, which proposes that feminine norm endorsement is a risk factor for body dissatisfaction and disordered eating in women, may also generalize to men. Clinicians should consider integrating gendered perspectives into treatments for men with eating disorders. Future research into the mechanisms through which gender role conformity influences body image and eating outcomes in males is necessary.