Government contracting with private service organizations has grown rapidly in the United States in the last 25 years. Advocates of contracting hope that it will spur competition among service agencies, lowering costs and improving service quality. In practice, however, contracting departs significantly from this competitive model. Instead, government and private agencies develop long-term relationships which can be considered regimes governed by specific norms and expectations. These regimes profoundly influence the delivery of services and the politics of contracting. This article analyses these regimes in the context of the contested nature of public authority. The article concludes with suggestions for reforming public policy to improve the performance and effectiveness of contracted services.