Purpose: The tripartite influence model (Thompson et al. 1999) proposes that internalized appearance ideals mediate the relationship between socio-cultural norms endorsing a tanned appearance and sunbathing. This study examined the extent to which socio-cultural norms lead to an idealization of darker skin, which in turn predicts sunbathing. This study also explored whether the relationship between an internalized muscular physique and sunbathing is moderated by sex. Methods: Adult males (N = 124) and females (N = 175) completed an online questionnaire measuring socio-cultural norms endorsing a tanned appearance, internalization of mesomorphic and tanned ideals, and sunbathing. Results: The internalization of a tanned ideal mediated between norms and sunbathing in both sexes, with a greater internalization of a tanned ideal associated with more frequent sunbathing in both sexes. Moderation analysis revealed that increased sunbathing was associated with a greater internalization of a mesomorphic ideal for males but a lesser internalization for females. A positive association was also found between the internalization of mesomorphic and tanned ideals in males. Conclusion: Overall, people who internalize a tanned ideal based on the perceived attitudes of others are more likely to sunbathe. This study extended current literature by suggesting that males internalize a tanned ideal and finding an association between internalized mesomorphic and tanned ideals in males.