A factor analysis of the Conners Teacher Rating Scale (TRS) using a large stratified random sample of 9,583 school children is summarized. Although this questionnaire is used primarily as a screening instrument for hyperactivity, previous factor analytic studies have tended to use small samples generally biased toward pathology. A revised factor structure is presented, with the aim of improving the utility of the TRS as a clinical screening instrument. The psychometric characteristics of the scale are evaluated via measures of internal consistency and random split-half analyses of the sample. Norms for composite factor scores, controlling for sex and age, are also presented. Contrary to earlier findings, a primary factor of Hyperactivity does emerge.Requests for reprints should be sent to R.