In the modern healthcare system, many different decision-makers interact to care for patients and manage operations. To clarify the roles and responsibilities of different decision-makers, we reviewed previous work that described the decision-makers in healthcare organizations and the decisions that they make. We searched online databases for articles that described decision making in healthcare and manually searched journals and the bibliographies for other review articles. We identified six key roles: doctors, nurses, front-line managers, middle managers, senior level managers, and the board of directors. We classified clinical decisions into three categories: diagnosis, treatment and therapy, and medication prescription and administration. We classified non-clinical decisions into five categories: budget, resource allocation, technology acquisition, service additions and reductions, and strategic planning. We then summarized these roles and responsibilities. We also conducted information-gathering interviews with 27 executives at 7 hospitals to collect details about these and related decisions. These activities yielded a comprehensive picture of which personnel in a hospital make which decisions. Since organizations are decision making systems, this comprehensive picture of decisions and their decision makers will be instrumental in not only analyzing the underlying conditions of the administrative processes in healthcare, but aid in developing tools that healthcare organizations can use to assess their own decision-making processes, and thereby design solutions.