We applied a cultural-ecological framework to examine retrospective accounts of the socialization of sexism among Mexican-heritage youth living in the United States. Specifically, we surveyed 802 Mexican-heritage college students from three universities (79.5% women, 20.5% men; M = 19.60 years old). Participants were surveyed to assess the extent to which they recalled hearing traditional gender messaging (TGM) from older relatives, similar-aged relatives (familial peers), and nonfamilial peers. In addition, they completed measures of ethnic identity centrality, ethnic identity typicality importance, and ambivalent sexism. Our results indicated that TGM was most frequently attributed to older relatives and least frequently attributed to familial peers. Current ambivalent sexist attitudes were positively related to TGM recalled from familial and nonfamilial peers but not older relatives; also, the association was marginally stronger for familial peers than nonfamilial peers. In addition, ambivalent sexism was positively associated with ethnic typicality importance and negatively with ethnic identity centrality. Our research highlighted the importance of considering cultural processes linked to sexism endorsement and provides a new measure of TGM socialization from multiple sources relevant for Mexican-heritage college youth. Familial peers may serve as role models to aid Mexican-heritage youth in challenging sexist attitudes. Also, Mexican-heritage college youths rejected sexist beliefs while holding strong Mexican ethnic identities. Altogether, our work underscored positive ethnic identity and familial (and nonfamilial) peers as buffers against internalizing sexism.