Prospective studies of intergenerational continuity in parenting quality remain scarce, with little attention given to the potential role of social competence as a mediator of continuity. This study examined social competence as a mediator in the pathway from 1st generation (G1) to 2nd generation (G2) parenting quality. A normative sample of children and their parents were assessed in childhood, and again 10 and 20 years later. Parenting quality of G1 parents was assessed at each time point with multiple informants, as was G2 social competence. G2 parenting was assessed at the 20-year follow-up for those who were parents. The mediational role of social competence in G1 to G2 parenting quality was tested via nested path analytic models, accounting for continuity and cross-domain relations. Social competence mediated the intergenerational relation of parenting quality; results were invariant across gender and ethnic minority status and were unchanged after controlling for age, IQ, socioeconomic status, rule-abiding conduct, and personality (i.e., constraint). The authors discuss results regarding developmental theories of close relationships and the potential for cascading benefits within and across generations from interventions to improve G1 parenting or G2 social competence.