Pay-for-performance programs in health care are widespread in low- and middle-income countries. However, there are no studies of these programs’ costs or cost-effectiveness. We conducted a cost-effectiveness analysis of a pay-for-performance pilot program in Tanzania and modeled costs of its national expansion. We reviewed project accounts and reports, interviewed key stakeholders, and derived outcomes from a controlled before-and-after study. In 2012 US dollars, the financial cost of the pay-for-performance pilot was $1.2 million, and the economic cost was $2.3 million. The incremental cost per additional facility-based birth ranged from $540 to $907 in the pilot and from $94 to $261 for a national program. In a low-income setting, the costs of managing the program and generating and verifying performance data were substantial. Pay-for-performance programs can stimulate the generation and use of health information by health workers and managers for strategic planning purposes, but the time involved could divert attention from service delivery. Pay-for-performance programs may become more cost-effective when integrated into routine systems over time.