Adolescent boys (n = 269) were assessed for levels of several risky behaviors related to the pursuit of muscularity, including substance use (anabolic steroids, prohormones, and ephedrine) dieting to gain weight, and symptoms of muscle dysmorphia (MD). The association between these behaviors and a variety of putative biological, psychological, and social risk factors were also evaluated. Concerning rates for lifetime use of steroids (2.6%), prohormones (4.5%), and ephedrine (6%) were found. Multiple regression analyses indicated that MD and sports participation significantly predicted substance use. Body dissatisfaction and body mass index were significant predictors of dieting to gain weight. Additionally, negative affect, media influence, and sports participation predicted symptoms of MD.