In recent years both philosophers and scientists have asked whether or not our current kinds of mental disorder—e.g., schizophrenia, depression, bipolar disorder—are natural kinds; and, moreover, whether or not the search for natural kinds of mental disorder is a realistic desideratum for psychiatry. In this dissertation I clarify the sense in which a kind can be said to be “natural” or “real” and argue that, despite a few notable exceptions, kinds of mental disorder cannot be considered natural kinds. Furthermore, I (...) contend that psychopathological phenomena do not cluster together into kinds in the way that paradigmatic natural kinds (e.g., chemical kinds and species) do; and, in light of this fact, I conclude that the normative ideal of natural classification—i.e. classifying real or natural kinds—is not appropriate as a general strategy for psychiatry. In the conclusion to this dissertation I propose an alternative way forward. Rather than assuming a priori that psychopathological phenomena cluster together into kinds, a more tractable and theoretically promising approach would be to first explain how particular kinds of experiences and behaviours—e.g, hallucinations, delusions, disorganized thinking, mania, low mood, etc.—are produced. (shrink)