A longitudinal prospective design was used to examine antisocial behavior, two aspects of the parent–child relationship, inept parenting, and adolescents’ beliefs in the appropriateness of monitoring as predictors of parents’ monitoring and change in monitoring during the high school years. A total of 426 adolescents provided reports of their parents’ monitoring knowledge during four yearly assessments beginning the summer before entering grade 9. Greater concurrent levels of monitoring knowledge were associated with less antisocial behavior, more parent-reported relationship enjoy-ment, adolescents and parents spending more time together, and adolescents reporting stronger beliefs in the appropriateness of parental monitoring. Weaker knowledge beliefs predicted increases in monitoring knowledge over time. More antisocial behavior problems were linked to lower levels of knowledge through less enjoyable parent–adolescent relationships, parents and adolescents spending less time together, and adolescents reporting weaker monitoring beliefs. Discussion focuses on processes linking antisocial behavior problems with low levels of monitoring knowledge.