This paper argues that the identity of history as a discipline derives from its distinctive combination of intellectual assumptions, or categories. Many of these categories are shared with other fields of thought, including science, literature, and common sense, but in history are understood in a unique way. This paper first examines the general notion of categories of historical understanding, then scrutinises some of the specific categories suggested by classic authors on the philosophy of history such as Dilthey and Collingwood. More recent works by Goldstein, Oakeshott, Bevir, and Tucker are treated as contributions to the same discussion. It concludes that the various categories these writers have proposed are neither trivial nor incompatible and that when collated they do indeed compose a framework capable of characterising historical thought.