Research supports both concurrent and prospective associations between peer behaviors and disordered eating levels in late adolescent and young adult men and women. However, no study has examined peer influence after a follow-up duration over which peer groups change dramatically. This study examined how college roommates' dieting predicted disordered eating levels in women (n = 566) and men (n = 233) at 10-year follow-up. For women, college roommates' dieting significantly predicted Eating Disorder Inventory Drive for Thinness and Bulimia scores and purging at 10-year follow-up. Findings highlight the potential for school-based, peer-led interventions to have long-term benefits in women.