There is no question: We are all persons. But what exactly are persons? Are we immaterial souls or Cartesian Egos which only contingently have bodies? Or are persons nothing over and above their bodies? Are they essentially or most fundamentally animals, evolved beings of a certain sort? Or are we something other or more than animals, namely constituted beings with a certain capacity that distinguishes persons from everything else? What is necessary, and what is sufficient, for an entity to be classified or (re-)identified as a person? What's the value of an analysis of such (biological or psychological) conditions? What does it contribute to our understanding of ourselves as free agents or as beings wanting to live their individual live? The essays collected in this anthology try to answer these questions. They are primarily concerned with the metaphysics of persons and the criteria of personal identity, but also touch on problems of the theory of action and of practical philosophy.