Abstract Family support has been demonstrated to be essential for successful long-term outcomes of low-income, African American adolescent mothers and their children [Apfel, N., & Seitz, V. (1996). Urban girls: Resisting stereotypes, creating identities. NY: New York University Press]. Family support may also be essential for the continued paternal involvement of unmarried, low-income, African American adolescent fathers. Twenty mothers of unmarried, low-income, African American adolescent parents were individually interviewed for this qualitative study to describe the experiences of paternal grandmothers (mothers of adolescent fathers) and maternal grandmothers (mothers of adolescent mothers) during transition to fatherhood for unmarried, low-income, African American adolescent fathers. Findings are presented according to the six factors of transition conditions from the nursing model of transitions [Schumacher, K., & Meleis, A. I. (1994). Image, 26, 119–127]: meanings, expectations, level of knowledge and skill, the environment, level of planning, and emotional and physical well-being. Findings indicate that transition to parenthood and grandparenthood is often abrupt and complicated for unmarried, low-income, African American adolescent parents and their families. Paternal and maternal grandmothers continue to act as primary parents for their adolescents while compensating for the lack of skills and attributes for the adolescents' children. Findings from this study can be used to design developmentally and culturally appropriate health care interventions that can support these families during this complex process.