For more than two decades, governments and development agencies around the world have focused on reducing poverty. Although tremendous strides have been made, approximately one in four people in developing countries continues to live below the World Bank_s international poverty line. Wise public investment is key to reducing poverty and addressing inequalities within society. That requires timely and accurate data to measure progress and plan for investment, as well as for good analysis and policy application. In much of the developing world, however, the lack of appropriate local information about the poor hinders development planning and programs, and constrains efforts to monitor change. It also impedes efforts to measure progress toward achieving the Millennium Development Goals (MDGs). For more than a decade, IDRC has supported researchers in 15 countries of Asia and Africa who have developed, tested, and implemented a community-based poverty monitoring system (CBMS). This book, and its accompanying website and enclosed CD, argue that good public policy choices for empowering and uplifting the poor are best made when local authorities and communities work together and are guided by sound data and evidence-based analysis. This is key to ensuring effective public spending and greater public accountability.