In this study, we aimed to replicate Stattin and Kerr’s (2000) study on parental monitoring and adolescents’ deviant behavior, to extend their findings to ADHD symptoms, and to examine the longitudinal predictors (8-18 years) of parental knowledge and child disclosure. Results showed that conduct problems were primarily associated with parental knowledge and child disclosure, but not with parental solicitation and control. A similar pattern was observed for ADHD symptoms. However, while the relations for conduct problems were generally independent of ADHD symptoms, the relations for ADHD symptoms were primarily non-significant after controlling for conduct problems. Moreover, early behavior problems, but not insecure/disorganized attachment, were associated with parental knowledge and child disclosure in adolescence. In conclusion, child disclosure is primarily associated with deviant behavior rather than ADHD, and early child problem behavior is a more important predictor of child disclosure (implicating reciprocal relations between these two constructs) than is insecure/disorganized attachment.