The Attention–Distraction, Inhibition–Excitation Classroom Assessment Scale (ADIECAS) [Evans, P. L. C. (1975). Inhibition and stimulus generalization in the discrimination learning of ESN(S) and ESN(M) children. Unpublished Ph.D. thesis. Manchester, UK: University of Manchester] assesses attention-related difficulties in children with intellectual disabilities (ID). The present study explored the psychometric properties of the ADIECAS with a sample of 84 children with moderate and severe ID whose teachers completed the ADIECAS and the Conners’ Teachers Rating Scale [Goyette, C. H, Conners, C. K., & Ulrich, R. F. (1978). Normative data on revised Conners’ parent and teachers rating scales. Journal of Abnormal Child Psychology, 6, 221–236]. Following factor analysis the Evans and Hogg [Evans, P. L. C., & Hogg, J. (1984). A classroom rating scale for use with mentally retarded children. British Journal of Clinical Psychology, 23, 187–194] structure was the most appropriate for use with this sample. Moderate to strong positive relationships were found between the ADIECAS and the Conners’, and the ADIECAS factors were significant predictors of the Conners’ subscales. This study provides further support for the ADIECAS as a reliable and valid measure of ADHD-related symptoms among children with moderate and severe ID.