The nature and correlates of psychological disorders of preadolescent children from the longitudinal Australian Temperament Project (ATP) are reported. Almost half of the children identified via checklists completed by mothers, teachers, and the children themselves as being in the at-risk range for disorder received a DSM-III-R diagnosis. Nine per cent of comparison, or low-risk, children also received a diagnosis. Internalising disorders were the most common, and 44% of cases had multiple problems. Children rated as problematic by all three informants or by child plus teacher were the most likely to receive a diagnosis. The at-risk group had more difficult temperament, poorer family and peer relationships, lower levels of social skills, and were of lower SES than the comparison group. There were minimal differences on these variables between at-risk children who did, or did not, receive a DSM-III-R diagnosis. It is argued that especially for boys, checklists from multiple informants are effective tools for identifying clinically significant disorders.