National Early Intervention Longitudinal Study (NEILS) | SRI International

Toggle Menu

National Early Intervention Longitudinal Study (NEILS)

For the U.S. Department of Education, SRI conducted a first-of-its-kind national longitudinal study of infants, toddlers, and their families receiving early intervention services.

From 1996 to 2007, SRI conducted NEILS for the U.S. Department of Education’s Office of Special Education Programs (OSEP). NEILS was the first national study of Part C of the Individuals with Disabilities Education Act (IDEA) early intervention program for infants and toddlers with disabilities, or at risk for developmental delay, and their families.

The study included a nationally representative sample of 3,338 infants and toddlers and their families. NEILS followed children from entry into the early intervention service system through kindergarten. SRI developed a comprehensive conceptual framework for the study that involved data collection about children, families, programs, service providers, and communities to address research questions about the characteristics of service providers in early intervention programs, the services that children and families received, and the outcomes they experienced.

The study designed and conducted annual parent telephone interviews with the sample (children ages 0-5). Special attention was paid to gathering data about indicators of children’s school readiness from a broad perspective (including social development, behavioral engagement, and health, as well as language and cognitive skills). Numerous reports and presentations were produced from these data, including reports for OSEP that were included in annual reports to the U.S. Congress.

The NEILS data are now available in the form of a public use dataset on CD-ROM. (To request a copy of the dataset, please contact cld [at]

Study Design

Five Major Research Questions

  1. Who are the children and families receiving early intervention services?
  2. What early intervention services do participating children and families receive, and how are those services delivered?
  3. What are the costs of these services?
  4. What outcomes do participating children and families experience?
  5. How do outcomes relate to variations in child and family characteristics and services provided?


A nationally representative sample of 3,338 children between birth and 31 months of age and their families who began early intervention services for the first time between September 1997 and November 1998 were recruited for the study. The sample families were recruited in 3 to 7 counties in each of 20 states. The NEILS states are shown in green on the map.

Survey Instruments



This study was made possible through funding from the Office of Special Education Programs in the U.S. Department of Education.

SRI would like to acknowledge and thank the families of children with special needs who so graciously agreed to be part of this study and gave their time to be interviewed. We also would like to thank the service providers and directors of early intervention programs around the country who recruited the families for the study and found time in their busy schedules to complete NEILS data forms. The study families and the service providers who work with them were the backbone of NEILS. The study would not have been possible without their cooperation and support. We thank them on behalf of the next generation of infants and toddlers with special needs who will benefit from their contributions.