Men's drive for muscularity refers to the degree to which men wish to increase their muscularity. Men who are more extreme in their drive for muscularity face dangerous consequences, such as increased levels of eating pathology and use of performance-enhancing substances. The aim of this study was to predict men's drive for muscularity, and to test whether hypothesized predictive factors vary across age groups. Participants were 226 men ages 18-67. It was hypothesized that body dissatisfaction would predict men's drive for muscularity. More substantively, however, it was hypothesized that having a strong tendency to compare oneself with others would exacerbate the relationship between men's body dissatisfaction and their drive for muscularity. Results of a hierarchical multiple regression analysis supported these hypotheses. Furthermore, this exacerbating effect was present regardless of men's age. Implications for assessment, clinical practice, research, and prevention efforts are discussed.