Research has identified links between parents' poor monitoring of adolescents' whereabouts and activities and adolescents' increased engagement in delinquent behaviors. This study extended prior work by examining differential relations between parental monitoring measures (i.e., behavioral vs. knowledge measures) and informants (parent vs. adolescent) and adolescent self-reported delinquency. Seventy-four caregivers and adolescents completed survey measures of parental monitoring and parental knowledge, and adolescents completed self-report surveys of delinquent behavior. Adolescents' delinquent behavior related to measures of parental monitoring behaviors and parental knowledge; however, the magnitudes of these relations varied by informant. That is, I observed stronger magnitude relations between adolescent delinquent behavior and parental knowledge measures for parent-report relative to adolescent-report. Conversely, I observed stronger magnitude relations between adolescent delinquent behavior and measures of parental monitoring behaviors for adolescent-report relative to parent-report. These findings inform measurement selection in research and clinical assessments of parental monitoring and adolescent delinquent behavior.