The South West Thames Regional Library Service (England) uses contracts for library service to encourage library cooperation, liberate staff, and focus on the quality of information services. The South Thames Regional Library Service facilitates access to and promotes the use of health care literature and is responsible for planning and commissioning library services for 60,000 National Health Service (NHS) staff, maintaining a framework for library cooperation, and providing logistical support to the libraries in the form of databases, networks, and professional development opportunities. In less than four years, the use of contracts has: doubled the use of the libraries, won budget increases of 50%, increased the professional autonomy of local library staff, and instituted a program of continuous quality improvement. Performance is monitored through quarterly activity returns, annual objective setting, annual structured library visits, and special surveys. Performance measures inform the dialogue between library service commissioners and providers, concentrate on key issues, and keep the "paymasters" happy. The report provides background on the changes in the NHS that resulted in changes in the provision of library services, and discusses each of the performance measures. Figures illustrate examples of library activity reports. A brief discussion with the author is provided. (SWC)