Abstract Fatherhood has become an achieved status among complex, disadvantaged families. Stepfathers may have an advantage over nonresident biological fathers in earning the father role; in-depth interview studies reveal that nonresident fathers are often stripped of the father label while stepfathers commonly achieve it instead. This stepfather advantage is surprising given extant institutionalization theory, which suggests that the stronger institutionalization of the biological father role should benefit nonresident fathers over stepfathers. Drawing on 55 in-depth interviews with adolescents and their primary caregivers, we recenter youth agency in family theory by exploring how some men and not others earn the father role from the perspective of their adolescent children. We find that the strongly institutionalized role obligations of biological fathers impeded rather than aided nonresident father-child engagement. When nonresident fathers did not meet institutionalized expectations, adolescents experienced psychological trauma and usually resisted their attempts to become more involved. In contrast, the incomplete institutionalization of the stepparent role benefited stepfather-stepchild relations by allowing stepfathers to flexibly adapt to complex family dynamics. Further, stepfathers more easily met, and even exceeded, their stepchildren’s limited expectations of them. Thus, stepfathers may face a lower cultural bar for and gain greater satisfaction from fulfilling the father role than nonresident biological fathers.