Public Law 99–457 extended the landmark Public Law 94–142 legislation to include early intervention for infants and toddlers with or at-risk for development of developmental disabilities. Currently over 300,000 infants and toddlers and their families in the United States receive services through Part C of the Individuals with Disabilities Education legislation. The law fostered interagency collaborations and included the child's parent or caregiver as an integral part of the intervention team. This article reviews the 26 years of legislation associated with educating young children with disabilities and the resulting early intervention service delivery system. Analyses and review of studies of Part C services are offered to inform policies that enhance early identification, family engagement, and intervention delivery. © 2012 Wiley Periodicals, Inc. Dev Disabil Res Rev 2011; 17:36–43.