African American youth from single mother families are at an elevated risk for externalizing difficulties, and yet are under-studied in terms of culturally-relevant health promoting influences on their adjustment or positive indices of adjustment. The current study utilized a mixed methods research design (quantitative data: n = 185; qualitative data n = 20) to examine associations between two parenting behaviors displayed by one health promoting influence, nonmarital coparents (i.e., adults identified as significantly involved in child-rearing), and indicators of both adjustment (self-esteem) and maladjustment (externalizing difficulties) among African American early adolescents from single mother homes. Quantitative findings provided support for a differential specificity parenting hypothesis involving coparent parenting behaviors. Coparent monitoring was significantly associated with youth externalizing symptoms but not self-esteem, and its association with externalizing symptoms was marginally stronger than its association with self-esteem. Coparent warmth was associated with both youth externalizing difficulties and self-esteem and significantly more strongly associated with self-esteem compared to externalizing symptoms. Qualitative findings from interviews with adolescent participants suggested that coparents were engaged in close, multi-faceted relationships with them, and, overall, those relationships involved a mixture of functions typically performed by both parental figures and mentors. Findings initially suggest that service providers may want to emphasize the benefits of coparents providing to youth from single mother families consistent social support and monitoring/re-direction, with the latter perhaps being most helpful in the context of a very close relationship between youth and coparents.