Empirical evidence supports parental monitoring as a moderator of adolescent problem behaviours. A methodological review shows that monitoring has been measured using self-report questions based on parental knowledge of adolescent free-time use; however, inconsistencies in the definition of monitoring have created confusion. A process model of parental monitoring is proposed. This proposed model conceptualises monitoring interactions in a temporal sequence. It proposes that parental monitoring occurs in two distinct stages: before the adolescent goes out and when they return home. Parental and adolescent responses to monitoring interactions impact on future monitoring episodes. The proposed model demonstrates that a functional understanding of parent and adolescent monitoring behaviours is essential to clinical prevention and intervention.