This chapter focuses on what engagement is not, clearly distinguishing it from other existing concepts. An in-depth and rich review of the theoretical and empirical differences between engagement and other constructs in its nomological network is provided to clarify how engagement is different, but also what it shares in common with other constructs. Tables 3.1 through 3.4 (all updated in this second edition) list correlations between engagement and related constructs, such as performance and commitment. Cracks in our understanding of engagement are exposed.