Maternal substance abuse is a serious problem with significant adverse effects to mothers, fetuses, and children. The Early Start Program provides pregnant women in a managed care organization with screening and early identification of substance abuse problems, early intervention, ongoing counseling, and case management by a licensed clinical social worker located in the prenatal clinic, where she is an integral part of the prenatal team. We describe the development of the Early Start Program, its administrative history, and how it has interfaced with clinicians and administrators. We also highlight two important program characteristics: the partnership with a perinatal health services research unit and the degree to which the program could be "exported" to other managed care settings.