As government has attempted to deal with complex social problems, the inevitability of error has become increasingly apparent to students of public policy and implementation. This essay focuses on errors of service, initially drawing on the experience of the Veterans Administration (VA) medical system to explore problems of defining, detecting and correcting such errors when government directly delivers care. It probes the complex blend of errors of liberality and stringency that appeared to be present in the VA during the 1970s, the formidable barriers to error correction, and the steps taken by the VA in response to the problem. Second, the essay examines whether a commercial market strategy, as embodied by Medicare or Medicaid, offers certain advantages in dealing with service errors similar to those confronted by the VA. The experience of Medicare and Medicaid casts doubt on whether a commercial market model yields superior results in coping with these kinds of error. Finally, the study points to some more general implications of the VA's experience for discussions of service problems in the health policy arena.