Alliances between managed care plans and public health agencies are a growing phenomenon in local health care markets, with profound implications for health care quality, cost, and accessibility. A typology of interorganizational relations between managed care plans and local public health agencies is drawn from observations of over 60 public health jurisdictions. Relations are described along three dimensions corresponding to the strategic intent, functional operation, and structural design of each alliance type. The identified models of interaction reveal the motivations for forming alliances, the mechanics of their operation, and the possible outcomes. These alliances suggest that a wide range of interorganizational strategies is possible in order to pursue the shared interests of local public health agencies and managed care plans. Nonetheless, public health agencies may face challenges in forging managed care alliances that benefit community-wide populations and that are open to participation by the full spectrum of health care providers in the community.