This Working Paper reviews the recent international debates on the role of the state in health system governance, and uses those discussions to establish the legitimate role of the state in ensuring the appropriate use of evidence for health policy making. Specifically it examines the concept of stewardship which has emerged within recent global health governance debates, applying this concept to the stewardship of evidence. The stewardship function of national ministries of health was originally introduced by the World Health Organization in the 2000 World Health Report, but has been subsequently debated by authors who have associated the concept with a range of government and service provision functions. This paper develops a clearer and more nuanced understanding of the concept of stewardship to differentiate it from the related, yet distinct, concept of governance. We argue that the unique, and therefore conceptually useful, aspect stewardship lies in the way it allocates a single ultimate responsibility for the health of the population. The WHO has further established that it is national ministries of health, specifically, which possess the legitimacy to assume the functions as stewards of population health. The stewardship concept has been established with a range of functional characteristics, including the appropriate use of information to guide health planning and decision making. Taken together, these elements have direct implications for conceptualising how to ensure appropriate use of evidence in health policy. Ministries of health, as population health stewards, tasked with appropriate information use, possess a responsibility to ensure health system decisions are appropriately informed by evidence. In order to do this, they must establish institutional structures and procedures that function to synthesise, disseminate and apply health information and research evidence for use in policy making.