Despite employee engagement’s centrality as a construct, clear theoretical and operational definitions are few and far between. We argue for re-conceptualizing engagement, grounding it in the vast psychological literature on human motivation. Herein lies the paper’s contribution; we argue that the apparent conceptual proliferation can be understood as attempts to draw ever nearer to key motivational concepts. We review engagement definitions and find that they are reducible to a comprehensive taxonomy of twelve human motives. We consider the impact of rooting engagement in existing motivational constructs for each of the following: (a) theory, especially the development of engagement systems; (b) methods, including the value of applying a comprehensive, structural approach; and (c) practice, where we emphasize the practical advantages of clear operational definitions.