Kuhn’s mature writings contain some interesting but rather underdeveloped insights about the process of specialisation, which is the topic of this chapter. I begin by discussing the formation of what Kuhn calls ‘scientific specialties’, the kind of incommensurability that drives such a phenomenon, and the relation between specialisation and scientific revolutions. My take on these topics draws from Kuhn’s philosophy but leads to conclusions that Kuhn himself could not see or failed to appreciate. I also I discuss interdisciplinarity, a phenomenon that Kuhn did not address, even though it threatens his ideas about the existence of an incommensurable divide among scientific specialties. Finally, I consider how the theory of specialisation enriches our understanding of Kuhn’s views on scientific change and of his remarks about the ‘plurality of worlds’.