Masculinity has been theorized to be an anxiety-provoking state. Consequently, many researchers have examined masculinity in relation to negative psychological outcomes such as anxiety, depression, and alcohol or substance use. However, emerging research suggests that certain facets of masculinity may also be related to positive psychological outcomes and that there is a need for more empirical research examining the differential impact of distinct masculine norms on both negative and positive outcomes. Accordingly, this study longitudinally examined the influence of masculine norms and gender role conflict on eudaimonic psychological well-being among young adult college men (N = 278). Participants were recruited from a public university and completed Time 1 (baseline) measures of masculine norm conformity and gender role conflict as well as Time 2 (6 months follow-up) measure of eudaimonic well-being. Results demonstrated that both masculine norm conformity and gender role conflict were predictive of increased and decreased well-being among young adult men. Specifically, the masculine norms of power and playboy were negatively associated with prospective well-being. In addition, gender role conflict, particularly restricted emotionality, was negatively associated with well-being. The norm of winning was positively associated with prospective well-being. In sum, men’s baseline adherence to traditional masculine norms was predictive of both positive and negative psychological well-being at follow-up, highlighting the differential impact of masculine norms on men’s health. The study’s theoretical and clinical implications, limitations, and future directions are discussed.