This book outlines an innovative approach to delivering development assistance for basic public services such as potable water, safe sanitation, modern energy, and primary education and health care. Called output-based aid, the approach delegates service delivery to the non-profit or for profit private sector under contracts that tie payments to the outputs or results actually delivered to target beneficiaries. Designed as a guide for aid practitioners and policymakers in developing countries, the book gathers cases of innovative, output-based approaches from across the infrastructure and social sectors, including construction of schools and IT learning facilities, energy, primary health care, roads, telecommunications, and water. These cases illustrate some of the key challenges in channeling tax and donor funds to target services and beneficiaries, and creating incentives for the efficient delivery of these services. The book concludes with a checklist for project implementation: including how to choose beneficiaries, how to choose service suppliers, how to define performance, how to link payments to performance and how to administer the schemes.