The Star Counting Test (SCT), an attention test for children, is presented. The test is suitable for groupwise administration. It was developed within a clear theoretical framework and focuses, in contrast to many current attention tests, on accuracy rather than speed. The test requires the control and alternation of two simple processes: forward and backward counting. In a prestudy, the reliability of the test appeared satisfactory. Substantial correlations were found with the Hyperactivity scale of the Conners Teacher Rating Scale and with grades for language and arithmetic. For the main study, a large scale assessment study of attentional deficits in Dutch elementary schools, three versions of the test were constructed. All versions of the test appeared reliable and substantial correlations were observed with the Attentional Behavior Scale of the Amsterdam Child Behavior Scale, a rating scale for teachers. Furthermore, the test was able to discriminate between various childhood disorders as rated by teachers. It was concluded that the SCT exhibits some essential characteristics that are needed for the measurement of individual differences in attention. The test can be used in large scale assessment studies and might be useful as a first screening device for attentional deficits.