This dissertation presents an attempt to work through Jacques Derrida's sustained engagement with psychoanalysis--in particular, his writings on Freud and on Jacques Lacan--from one end of his work to the other. It elaborates a new critical reading of Derrida's work organized around his repeated returns to the enigmatic figure of the death drive in Freud, one of the least considered aspects of Derrida's thinking. The death drive, I show, is Freud's attempt to envision a force present in the living, but antithetical to life, a drive opposed to the drives that sustain organic life. At the same time, Freud views this death or destruction drive as a type of aggressivity central to the formation culture. Tracking Derrida's thinking on the death drive across his work, I demonstrate how this figure and the notion of "life death" it suggests come to be at the center of Derrida's engagement with Freud. Through close readings of Derrida's work, I trace how he reads Freud's writing against itself, locating there something Freud himself does not entirely think through. The dissertation argues that an understanding of Derrida's thinking on the death drive equally allows us to reassess his relationship to Lacan, pointing to a certain proximity between Derrida and Lacan readers have consistently missed. What emerges from this reading of Derrida's work is a different perspective on Freud's theory, one that entails a reconfiguration of our basic conceptions of life and death. Death, here, is not opposed to the life drives, but internal to them, so that life is inherently divided against itself. On this view, life is haunted by a kind of "death" that continually disturbs it. At the same time, this reading sheds light on the profound ethical questions raised in Freud's thinking on this death or destruction drive. Turning to Derrida's late work on Freud and the moral law of "civilization," written at a moment he began to explicitly address notions of justice and responsibility, I outline how Derrida finds in Freud a rethinking of ethics as it has traditionally been conceived. The dissertation argues that in thinking life and death, ethics and violence, as constitutively bound up with one another, Derrida's return to Freud alters our inherited ways of understanding these terms.