This chapter defines health care and public health as two different policy sectors. Harkening back to the concept of sectoral paradigms, the chapter discusses how health care and public health can be defined as two different policy sectors, which overlap however regarding important policy challenges. To analyze the horizontal relations of policy sectors comparatively and to find different forms of sectoral overlap, the chapter defines different degrees of sectoral coupling based on the literature on coupling in organizational systems and institutional analysis. Then, it organizes the different forms of coupling into a two- dimensional ideal-typical analytical space with four different degrees of sectoral coupling – namely tight coupling, loose coupling, de-coupling, and non-coupling – at the extreme corners of the analytical space.