H. G. Wells was one of the most celebrated writers in the world during the first half of the twentieth century. Famed for his innovative fiction, he was also an influential advocate of socialism and the world state. What is much less well-known is that he was a significant contributor to debates about the nature of social science. This article argues that Wells’s account of social science in general, and sociology in particular, was shaped by an idiosyncratic philosophical pragmatism. In order to demonstrate how his philosophical arguments inflected his social thought, it explores his attack on prevailing theories of race, while also highlighting the limits of his account. The article concludes by tracing the reception of Wells’s ideas among social scientists on both sides of the Atlantic. Although his programme for utopian sociology attracted few disciples, his arguments about the dynamics of modern societies found a large audience among social scientists and political thinkers.