How can we measure the performance of different health systems, and how can we use such information to support ongoing health systems improvement? These are the central questions addressed in this volume. Health policymakers have a growing interest in finding ways of encouraging health systems to improve their performance, where performance is measured against quality, efficiency, or equity goals. Improving performance has the potential to reduce the tensions between rising demands and limited resources. There is also a growing demand for accountability among those who fund and those who provide health services. This book highlights the core elements of a possible performance measurement framework to assess health systems at the international and national levels. It also addresses further challenges which remain: how do we overcome the lack of health outcome measures? How do we better align performance information and incentives with policy objectives? And how do we reconcile the traditional professional self-regulation approach with greater public accountability for health care quality?