Previous longitudinal research has shown that parental monitoring is a powerful predictor of child outcomes. Children from families with low levels of monitoring are particularly at risk for antisocial behavior, difficulties in school, and related problems. We studied whether parental monitoring-as reported by mothers/stepmothers, fathers/stepfathers, interviewers, and teachers-differs across two-parent biological families, stepmother families, and stepfather families. Two-parent biological families were hypothesized to have higher levels of monitoring than stepparent families. Controlling for demographic differences, two-parent biological families showed higher levels of monitoring than stepfather families but did not differ significantly from stepmother families. The significant difference between stepfather and two-parent biological families involved the length of the relationship: biological families in shorter relationships demonstrated higher levels of monitoring than stepfather families.