This paper reports data relating to the development of a screening test for language impairment in 2 1/2-year-old children. The screening test itself has previously been described. The results of a pilot study and a larger community study are reported. In all, 34 children were included in the pilot study and 1015 in the community study. The reference test selected was the Reynell Developmental Language Scales and the cut-off adopted 1.5 standard deviations below the mean for either the expressive or the receptive scale of the test concerned. The pass mark on the screening test was ascertained using receiver operating characteristics (ROC). The validity is reported given the cut-off identified. The specificity, sensitivity and both positive and negative predictive abilities are reported for both the pilot and the subsequent study. The application of the test is discussed in the context of the current debate about early identification.