This study examined how Mexican American youths' extent of sibling caretaking is related to their personal and school adjustment, and whether mothers' gender-role attitudes and youths' familistic beliefs moderate these associations. One hundred and ninety-five Mexican American youth ("M" age 14.8 years; 64% girls) and their mothers participated in the study. Youth completed questionnaires about their extent of sibling caretaking, their educational aspirations, school involvement, school absences, grades, and their prosocial tendencies. Results indicated that, when examined singly, frequent sibling caretaking was related to youths' higher educational aspirations, greater prosocial tendencies, and more school engagement for older youth, but also to more school absences. When extensive sibling care was coupled with mothers' sex-stereotyped attitudes, youth experienced poorer outcomes. Youth who held strong familistic beliefs and were highly involved in sibling care reported lower educational aspirations, particularly girls. Findings underscore the importance of considering socialization influences when evaluating associations between sibling caretaking and youths' development.