This paper aims to understand the DSM-5 through situating it within the context of the historical development of the DSM series. When one looks at the sets of diagnostic criteria, the DSM-5 is strikingly similar to the DSM-IV. I argue that at this level the DSM has become ‘locked-in’ and difficult to change. At the same time, at the structural, or conceptual, level there have been radical changes, for example, in the definition of ‘mental disorder’, the role of theory and of values, and in the abandonment of multiaxial approach to diagnosis. The way that the DSM-5 was constructed means that the overall conceptual framework of the classification only barely constrains the sets of diagnostic criteria that it contains.