This document discusses the role of contracting in improving health systems performance. It describes how health systems have evolved in developing countries over time, with more diversification of actors and separation of roles. Contracting is presented as a tool that can help formalize agreements between health system actors and encourage coordination. The document examines different types of contractual relationships and argues that a contractual policy framework is needed to guide individual contracts. It also explores the role of the state as both an actor in contracts and a regulator of contractual relationships. Lessons are drawn from experiences using contracting in both developed and developing countries.