The implementation in Connecticut of Early and Periodic Screening, Diagnosis and Treatment (EPSDT), a program of comprehensive medical care for needy children, illustrates the complexities engendered by federally mandated state-administered health programs. The EPSDT amendments to Title V and Title XIX (Medicaid) were ambiguous on four major issues: administrative responsibility, costs, eligibility, and scope of services. The problems experienced by federal, regional, state, and local administrators in resolving these issues illustrate the weaknesses inherent in federal-state relations, and the contrasting roles health and welfare agencies under Medicaid have played in the development of health policy.Connecticut may represent maximum limits to state performance in carrying out EPSDT because it is a rich state, ranking high in medical resources and in the provision of Medicaid services. During the first year of implementation of EPSDT, the program had little impact: less than 5 per cent of eligible children were served. State policies, which contravened federal policy, precluded effective resolution of the legislative ambiguities; no new services were added, the organization of health services remained unchanged and fragmented; and the State Health Department played only a limited role.