This paper reviews and critiques the origin and development of a new specialty in sociology, the sociology of social problems. While social problems long has been a topic of sociological attention, it is only since the work of Blumer and, most especially, Spector & Kitsuse in the early 1970s, that a theoretically integrated and empirically viable tradition of writing and research has developed. The central proposition of this tradition is that social problems are the definitional activities of people around conditions and conduct they find troublesome, including others' definitional activities. In short, social problems are socially constructed, both in terms of the particular acts and interactions problem participants pursue, and in terms of the process of such activities through time. The founding theoretical statements are reviewed and the research is discussed in terms of the following categories: containing trouble and avoiding problems; the creation, ownership, and processing of problems; public regulatory bureaucracies and legal institutions; medicalizing problems and troubles; and social problems and the media. The paper closes with an overview of problems and insights of the perspective. There is a bibliography of 105 items.