In the 12 years since the passage of Public Law 99-457, early intervention systems have greatly expanded and are now stabilizing. This article examines the resulting entitlements for infants, toddlers, and preschoolers currently extended by all states. Perspectives from the legislative process, federal and state implementation, judicial interpretation, and professional views are included. Distinctions among the key provisions for differing early intervention service systems are presented. Influential Office of Special Education letters and significant legal cases are reviewed. Finally, essential standards for viewing entitlements are presented to assist an interdisciplinary audience to explore the question, "Entitled to what?".