Purpose: The Early Childhood Longitudinal Study-Kindergarten Cohort (ECLS-K; U.S. Department of Education, 2000) includes comprehensive assessments of home, classroom, and school contexts and developmental outcomes for a nationally representative sample of more than 20,000 children who began kindergarten in 1998-1999. The purposes of this article are to describe the ECLS-K and provide an example of how to use these data to advance speech-language-hearing research. Method: Special education questionnaires were analyzed from subsamples of children with diagnosed disabilities. The frequencies of different disabilities at kindergarten, 1st, 3rd, and 5th grade were calculated, and for children whose primary diagnosis was speech-language impairment, special education experiences were summarized. Results: There are relatively large subsamples of children with learning disabilities, physical disabilities, and speech-language impairments. Among children with speech-language impairments, there is substantial variability in special education experiences with regard to the amount of time children received services, location of services, types of instructional methods, and extent to which modifications were made to the general education curriculum. Conclusion: The comprehensive assessments, large subsamples of children with diagnosed disabilities, and detailed information about special education services makes the ECLS-K a useful resource for advancing the development of theory, effective classroom practices, and evidence-based policies that promote the well-being of children with special needs.