The concept of desert is familiar to everyone. We have all heard that wrongdoers deserve punishment, that the virtuous deserve happiness, that hard workers deserve success, that innocent victims deserve compensation, that everyone deserves an adequate level of medical care, that no one deserves to be born handicapped, and so on. ;From these sayings, it is clear that desert is an evaluative concept. It therefore belongs to the class of concepts that includes rightness, justice, rationality, goodness, beauty, and others. Desert (...) is thus a familiar, evaluative concept. ;It is ironic, then, that desert has not received anything like the amount of philosophical attention enjoyed by the other evaluative concepts that I mentioned. In this dissertation, I focus my attention on desert. ;I begin, in Chapter 1, by trying to explain why desert has been neglected by philosophers. In Chapter 2 I argue that much of the received philosophical wisdom about desert is false. Chapter 3 is dedicated to "institutional" theories of desert. These theories make desert relative to institutional rules or purposes. Chapter 4 explores some views about the purported connection between desert and the emotions. In Chapter 5 I argue that a well-known attempt to justify desert-claims fails, and that this failure is the result of mistaken views about the connections between desert and the concepts of moral obligation and of value. One aim of Chapter 6 is to reveal the defects of some prominent theories of desert of wages. A deeper aim is to expose a fundamental defect in a standard way of looking at desert in general. ;In Chapter 7, I present my own theory of desert. It contains, among other things, a catalogue of bases for desert and an explanation of "all-in desert" in terms of "prima facie desert" and "weight." The structure of my theory of desert is therefore similar to the structure of W. D. Ross's theory of moral rightness. (shrink)