Along with resource generation, financing, and health service delivery, stewardship is a key health system function. However, very little empirical analysis has been carried out on it. This paper aims to fill this gap in the literature by assessing the Ministry of Health's (MoHs) role as a steward of the Spanish National Health System (NHS) after the 2001 decentralization reform of health care management to the Autonomous Communities. We use the following stewardship framework with six sub-functions for the analysis, looking at the MoH's ability to: (1) formulate strategic policy framework; 2) ensure a fit between policy objectives and organizational structure and culture; (3) ensure tools for implementation; (4) build coalitions and partnerships; (5) generate intelligence, and (6) ensure accountability. We describe the stewardship function, identify existing challenges and issues in the Spanish case, and reflect upon methodological aspects of this exercise. We use reports, documents, articles, and official statistics to complete the analysis. Overall, we find the MoH to give an average performance in its role as the steward of the health system. The MoH has progressed particularly well in generating intelligence as well as formulating a strategic policy framework over recent years. However, it lacks the appropriate authority to efficiently coordinate the health system and to ensure that the Autonomous Communities implement policies that are in-line with overall NHS objectives.