In recent years, significant progress has been achieved in delivering health-related interventions that are designed to achieve goals relating to improving maternal and child health, and reducing mortality and illhealth due to HIV/AIDS, tuberculosis and malaria. It is increasingly apparent, however, that the gains have been neither universal nor sufficiently broad-based and sustainable. Progress at the national level has not necessarily resulted in gains for most vulnerable population groups; in some instances, progress has stagnated or been reversed. There is mounting evidence that health systems that can deliver services equitably and efficiently are critical for achieving improved health status. Thus, many global health initiatives now incorporate attention to health systems strengthening in the support they provide to countries. While this increased attention to the strengthening of health systems is welcome, it would not be sustainable in the absence of a sound monitoring strategy that enables decision-makers to accurately track health progress and performance, evaluate impact, and ensure accountability at country and global levels. Moreover, the use of results-based financing mechanisms by major global donors has created a further demand for timely and reliable data. There is also increasing in-country demand for data in the context of annual health sector reviews.