OBJECTIVE: The authors examined the discriminant validity of the diagnosis of attention deficit disorder with hyperactivity. METHOD: They used standardized rating scales of life stresses and child and family functioning to assess psychosocial and family risk factors in 47 children who had the diagnosis of attention deficit disorder with hyperactivity, a matched group of 47 children in the community, and a matched group of 47 children seen in a psychiatric clinic. RESULTS: Children who had the diagnosis of attention deficit disorder and children in the psychiatric clinic reported significantly more depression and anxiety than did the children in the community; furthermore, children diagnosed as having attention deficit disorder with hyperactivity had more externalizing symptoms than did children in the psychiatric clinic. Children diagnosed as having attention deficit disorder with hyperactivity plus a comorbid anxiety or depressive disorder had higher levels of coexisting life stresses and parental symptoms than did children who had the single diagnosis of attention deficit disorder with hyperactivity. CONCLUSIONS: These results underscore the need for future studies to carefully assess children diagnosed as having attention deficit disorder with hyperactivity for concurrent psychiatric disorders as well as family and psychosocial stressors that may contribute to childhood symptoms. Such information is essential because different subtypes of attention deficit disorder with comorbid disorders may arise from different etiologic pathways, may require varying treatment options, and may foreshadow different eventual outcomes.Abstract Teaser