As a result of federal law Public Law 99-457, Illinois has the opportunity to provide early intervention for at-risk children up to 3 years of age. These children have developmental delays, such as cerebral palsy, or are cocaine or alcohol babies. The legislative history and current status of Public Law 99-457 as it relates to the planning of early intervention services in Illinois is discussed. The document then describes ways in which a comprehensive Illinois system of early intervention services might work for families in accordance with Public Law 99-457. Recommendations and rationales for establishing such an early intervention system in Illinois are posited around three critical decision areas. These areas are: (1) eligibility, which defines which children will have a legal right to early intervention; (2) structure at the community and local level, which defines the ways in which eligible children will be found and served; and (3) finance, which defines what Illinois will pay for an early intervention mandate. (BB)