The hypothalamus is a small brain structure, which despite its size acts as a master homeostatic regulator, controlling energy and fluid balance, thermoregulation, sleep-wake states, stress responses, growth, and reproduction, as well as emotional and social behaviours. The hypothalamus can perform this plethora of complex functions because of its staggering neuronal diversity, with hundreds of different neuronal cell types. While our understanding of the adult hypothalamus is relatively advanced, there are major knowledge gaps in our understanding of how its immense neuronal diversity is established. Our studies are aimed at contributing to the decoding of hypothalamus development, focusing on the epigenetic and transcriptional control of this process. I will present our ongoing work aimed at understanding the role of the Polycomb epigenetic complex and the Tead1 transcription factor during mouse hypothalamus development.