Pediatricians can play an important role in the early recognition and prevention of psychopathology; however, no studies have carefully examined the pediatrician's ability to recognize behavior problems among preschoolers, a group with whom they have frequent contact. Through a consortium of pediatricians involved in office-based research, this study will examine: 1) how accurately pediatricians identify preschooler's behavior problems; 2) the pattern of pediatricians' referrals of preschoolers to mental health specialists; 3) the pattern of pediatricians, referrals of preschoolers to medical specialists, and how is this influenced by the accuracy of their diagnosis of behavior problems; 4) patterns of utilizing primary pediatric care among preschoolers with behavior problems, both accurately and inaccurately diagnosed; 5) whether families comply with referrals to mental health practitioners; 6) whether pediatricians can detect problems exhibiting short-term stability better than more transient problems. The design follows a two-stage approach. In the initial stage, 4000 children ages 2-5 will be screened during a visit to their pediatrician's office. The pediatrician will indicate whether the child has a behavior problem, and the child's mother will complete a behavior problem checklist. 300 children above the 90th percentile and 300 children below the 90th percentile on the behavior problem checklist will be invited to a thorough second stage evaluation involving play observations, questionnaires, parental interview and the child's intelligence testing. Two psychologists will review the material and reach a consensus opinion.about the presence of behavior-problems. The pediatricians' ability to identify behavior problems will be examined by comparing their opinions with the consensus diagnosis given by the psychologists. Further data analyses will examine referral and management patterns (derived from chart review) among children accurately and inaccurately diagnosed.