This report re-evaluates evidence on the issue of age ranges served of handicapped children in Illinois schools, analyzes additional research on the issue, and estimates the cost that would be incurred if the current 3-21 year range were to be lowered to birth. A literature review addresses two broad areas: the identification and effectiveness of services provided to children from birth to 3 years of age (including studies of prevention and early intervention) and special education costs and cost effectiveness (including a comparison among the states). A cost estimation model is presented and used to derive an estimate of costs for expanding the special education age range below 3 years. It is concluded that, pending the results of further studies, the current mandatory age range of 3-21 should remain. (CL)