This chapter revisits some of the central concepts related to vulnerability as it relates to climate change. It provides a brief background on vulnerability thinking, its evolution and related policy instruments. The different understandings of vulnerability often correspond with different prototypes of vulnerability assessments, which are used in political practice. These are briefly presented, as they will matter for the examination of the empirical cases. The chapter then explains why social vulnerability was chosen as one key concept relevant for studying adaptation. Drawing from works in the political ecology, this understanding is adjusted by also pointing to critiques of the social vulnerability paradigm and discussing vulnerability as a relational, embodied experience. Next, it is summarized how social vulnerability research has been unfolding in China and the United States and with it, some of the dominant constructions of vulnerability are presented. From this, the chapter extracts three syntheses, which guide the research of the book: 1) The need to explore vulnerability as a relational concept and engaging in a systemic thinking, 2) exploring drivers of social vulnerability origins across different political systems and 3) pairing dominant social vulnerability conceptions with views of local decision-makers.