The adult prostate is a glandular epithelium consisting of three main cell types: basal cells (BCs), luminal cells (LCs) and rare neuroendocrine cells. During prostate development, homeostasis and regeneration, the turnover of these cells is mediated by populations of multipotent and unipotent stem cells, but the precise lineage hierarchy between them is unclear. Now, Cédric Blanpain and colleagues uncover the cellular dynamics underlying postnatal prostate development in mice. They first provide a detailed morphometric analysis of postnatal prostate development, revealing that the overall branched ductal network of the adult prostate is established during early postnatal development, whereas tissue expansion and growth take place during pubertal development. In line with this, they report that cell proliferation and cell fate decisions are regulated in a spatiotemporal manner. Using lineage tracing, the authors further show that multipotent BCs are present along the ductal trees during early postnatal development and contribute to both BCs and LCs; this multipotency then becomes spatially restricted to the ductal tips as development proceeds. Around the onset of puberty, BCs undergo a switch from multipotency to unipotency, with LC expansion then being fuelled by unipotent luminal SCs. Overall, these findings provide key insights into the spatiotemporal regulation of prostate development and further our understanding of cell potency in the context of prostate regeneration and tumorigenesis.