The classification of the sciences is one of the most discussed and analysed aspects of Peirce’s corpus of work. I propose that Peirce’s attempt at systematising the sciences is characterised by a distinctive historicity, which I construe in two complementary senses. First, I investigate Peirce’s classification as part of a broader nineteenth-century move toward classifying the sciences, a move that was at the same time motivated by social and epistemological goals. I claim that this re-contextualisation adds an entirely new layer to the otherwise distinctively internalist readings of Peirce’s classification. I then look at how Peirce’s scheme, especially in the form it displayed in the early 1890s, relates to his own historical writings, particularly his history of science. Looking at Peirce as a historical actor in his own right through the lens of his classification, I claim, is indispensable to understand the contemporary relevance of his contributions to the history and historiography of the sciences.