According to the tripartite influence model, body dissatisfaction is shaped by internalizing cultural appearance ideals stemming from appearance-related family, peer, and media pressures. This model was developed for women, but emerging evidence points to its relevance for men's body image. This study advanced this budding research by (a) integrating muscular-ideal internalization alongside lean-ideal internalization and body surveillance into the model, (b) examining two positive dimensions of body image as outcomes (body image quality of life and appearance evaluation), and (c) testing this model in national online sample of 5293 men. Structural equation modeling supported the model. Family, peer, and media pressures related to higher lean-ideal internalization, which related to higher body surveillance and poorer body image outcomes. Peer and media pressures related to higher muscular-ideal internalization, which related to higher body surveillance but more adaptive body image outcomes. We further examined whether model variables and paths differed based on men's body mass index (BMI). Men with higher BMIs evidenced a stronger path between body surveillance and body image outcomes. These findings highlight the usefulness of sociocultural models for understanding men's body image experiences.