Current research on Mexican immigrant women’s health reports a myriad of preventable health problems that could be prevented with physical activity. Research also indicates that these women experience a multitude of barriers to participating in physical activity including cultural beliefs. It is significant to investigate the foundations of cultural beliefs because they are the ideologies that inform health behaviors like physical activity. The aim of this study is to investigate the effect of cultural beliefs on physical activity behaviors of Mexican immigrant women. Using surveys and individual interviews, the researcher investigated the cultural beliefs surrounding marianismo or the roles and responsibilities of motherhood, wifehood, and womanhood for Mexican women. The significant finding was that marianismo beliefs negatively affected their physical activity level especially within their roles as mothers and wives. Spousal support for these women was crucial in overcoming the marianismo barrier to physical activity.