Arnett’s (2000) theory of emerging adulthood has been both widely celebrated and strongly criticized. However, it has not yet been closely scrutinized for what it claims to be: “a new theory of development for the late teens though the twenties.” The purpose of this chapter is to take up this scrutiny, evaluating some of the major postulations and criticisms of emerging adulthood in light of the available evidence. In particular, the chapter focuses on three broad claims pertaining to emerging adulthood: (1) that it is a developmental stage, (2) that it is a theory, and (3) that it is nonsense. The analysis presented in the chapter is not meant to resolve the debates in the field but rather to examine the nuance and celebrate the complexity of the questions in order to stimulate further theory and research on the topic.