The 1990 National Health Service and Community Care Act introduced sweeping changes to health and social welfare services. The reforms to community care were dominated by the introduction of markets for social care. We argue that the new markets cannot be guaranteed to deliver the range of services required to meet community care objectives. When they began to assume their new responsibilities, few key purchasers had a basic understanding of the functioning and imperfections of markets. Consequently, they were poorly equipped to anticipate or ameliorate the sources of market failure that we identify. Like any other relatively ill-informed purchaser, local authorities risk being unable to buy what they want on behalf of their residents and at an appropriate volume, cost and quality. We discuss where and how market imperfections are likely to occur. In this context, we offer an economic framework to help in the shaping and managing of social care markets.