Since the early discussions of polycentricity, the concept (and variations such as polycentric political systems, polycentric governance, polycentric order, etc.) has seen the development of numerous permutations, digressions, and contradictions. This chapter is meant to carefully step through key notions tied to polycentricity and polycentric governance. The chapter’s purpose is to discuss polycentric governance in particular, while giving some attention to polycentricity as a term from which polycentric governance originates. We build upon the classic version of polycentric governance as a 'polycentric political system', link this concept with broader conceptualizations of polycentricity, and survey the related ideas that have been investigated around the concepts of polycentric political systems, polycentric order, polycentric governance, and polycentric arrangements.