Family science brings new perspectives to the study of masculinity in the social sciences and public health. Families are spaces to both examine and to change expectations for masculinity, in part through encouraging the expression of multiple masculinities. In this article we identify two unique theoretical contributions of family science: reconceptualizing masculinities as family-level processes, and as intergenerational processes that emerge over time. We situate the social construction of masculinities within family relationships over time, as well as in structural contexts and institutions guided by laws and policies. Finally, we provide four dimensions of masculinities as tools for new research: families and enabling of hegemonic masculinity; families and development of alternative masculinities; mental health consequences of family-level masculinity processes; and expanding masculinities beyond the body with a gender-inclusive approach.