In this introductory session, the core twelve domains of health systems science (HSS) will be defined and the historical evolution of HSS that has resulted in the development and implementation of HSS into medical education will be described.  The necessary characteristics of health systems and providers that are grounded in HSS tenets will be discussed. This session will set the stage for the remainder of the series, which will more particularly address incorporation of HSS into undergraduate and graduate medical education, culminating in a final session describing challenges that have been faced.