Psychosocial dysfunction in children, first recognized more than 20 years ago as the "new morbidity" in pediatric practice, is now the leading cause of disability in childhood and adolescence.(15-17, 30) Epidemiologic research indicates that 14% to 20% of American children have one or more psychiatric disorders in the moderate to severe range,(10) and the overall prevalence is rising.(1) As many as half of all pediatric office visits reflect behavioral, psychosocial, and educational concerns, and most children in the United States with a psychiatric disorder receive care only from their pediatricians, making primary care clinics the "de facto mental health service" for most children in need of such care.(14) In addition, with the advent of managed care, pediatricians are increasingly becoming "gatekeepers" who identify and refer children with mental health problems. Despite the growing prevalence of psychiatric illness in children, four out of five children with diagnosable behavioral and emotional problems are not identified by their pediatricians, and even fewer receive mental health services.(14) Furthermore, children are more likely to be recognized and treated if their behavior upsets or annoys adults than if their psychiatric symptoms lead to school failure and poor functioning at home. Poor children are among the least likely to receive adequate mental health attention.(44) Numerous studies have shown that untreated mental health problems result in high rates of medical services(29) and place children at high risk for chronic psychosocial morbidity, including antisocial and self-injurious behavior.(31, 33, 40) Some obstacles to recognition by pediatricians are long-standing. Parents may be reluctant to raise psychosocial concerns, pediatricians map wish to avoid stigmatizing labels, pediatric training underemphasizes mental health and behavioral problems, and reimbursement for psychosocial services is low or unavailable for pediatricians. New hurdles have emerged as efforts to contain medical costs, such as managed care systems and capitation, have led to shortened office visits, larger panel sizes, constraints on referrals, and even disincentives to recognize children in need.(23) This introduction describes the most common psychiatric conditions presenting to pediatric clinics and discusses approaches to identification, assessment of severity, and treatment planning. Within treatment planning are highlighted guidelines for consulting a pediatric psychopharmacologist because medication is often an important feature of a comprehensive treatment plan.