The Supports Intensity Scale-Children's Version (SIS-C)was developed to assess the support needs of children and youth aged 5 to 16 years with intellectual and developmental disabilities. Data from the standardization sample of the SIS-C were analyzed to evaluate the impact of the age cohorts (5-6, 7-8, 9-10, 11-12, 13-14, and 15-16 years) used to stratify the sample on the measurement model, as well as the latent means, standard deviations, and correlations. The findings confirmed measurement invariance across age cohorts, but suggested that at the latent level, younger children, generally, have more intensive support needs and that as students with intellectual disability age, their support needs decrease. In addition, the 15- to 16-year-old cohort displayed differences in terms of the strength of correlations between support need domains, with stronger correlations than the other age groups. Implications for future research and practice are described. [This article was published in "Psychology in the Schools."]