Evolving market forces are reshaping current patient, parent, provider, insurer, and hospital relationships. The traditional individualistic focus for accountability and responsibility is being supplemented by population-wide responsibilities and accountabilities. These changes, often lumped together as "managed care", are being implemented with evolving ideas on how best to manage an organize collaborative activity. In this article it is reasoned that perinatal services will improve as objective outcome measures guide the development, evolution, and operation of competing managed care networks. The article illustrates how a managed perinatal care network works with experiences drawn from the perinatal service programs of Kaiser Permanente's Southern California Region.