Most scholars, following Rousseau himself, have had little to say about what Rousseau calls “the desire to extend our being.” Yet the concept is foundational to his political philosophy. Though less compelling a formulation (and deliberately so) than Plato's “eros” or Nietzsche's “will to power,” “the desire to extend our being” is comparable to these in its strength and reach, and hence in its power to unlock the full meaning of Rousseau's thought. My purpose in this paper is to uncover Rousseau's view of the meaning and significance of this desire; its pervasive influence on moral and political life; and the means through which it can and cannot, and should and should not, be fulfilled.