Diabetes carries a major health burden worldwide, and improving treatment and management of the disease requires an in-depth understanding of the development, homeostasis and physiology of the pancreas and of β-cells. Much of our knowledge to date comes from studies in the mouse, but there are significant differences between mouse and human, and it is unclear to what extent principles learned in the mouse can be applied to human. The pig represents a potentially better model than mouse, but very little is known about pig pancreas development. Here, Seung Kim and colleagues report a detailed transcriptomic and morphological analysis of pig pancreatic islets at various stages of development – revealing close similarities to human cells in terms of transcriptional profile and islet formation. They also find new evidence for developmental signalling between islet cells, providing a platform for discovering key signals controlling islet growth, survival and functional maturation. These data provide a valuable resource for the further development of the pig as a system for understanding pancreatic development, which could improve efforts in islet cell replacement and modelling diabetes.