The development of the cerebellum and its connections is a pivotal process that extends from embryonic to early postnatal stages. Cerebellar disruptions during this critical period are often associated with neurological impairments, impacting motor, cognitive and social behaviors. Despite advances in understanding cerebellar specification and function, the precise mechanisms underlying the development and organization of cerebellar neuronal subsets into functional brain circuits remain poorly understood. A comprehensive description of the activity events occurring during early cerebellar development and how their alterations could affect cerebellar circuitry is particularly lacking. This is a crucial question, as transient alterations in activity during critical developmental periods can lead to persistent changes in structural and functional connectivity, potentially contributing to the development of diverse complex pathophysiological conditions originating from the cerebellum.In this study, we explore the emergence of spontaneous calcium activity in the cerebellum. Using transgenic mouse models and advanced imaging techniques, we describe characteristic patterns of cerebellar activity during embryonic and early postnatal development. Our findings highlight the significant involvement of the cerebellar nuclei in this early activity rise. Moreover, we observe dynamic shifts in the patterns of activity from embryonic to perinatal stages, suggesting their potential role in the establishment and refinement of cerebellar circuits during early postnatal development.In conclusion, describing and gaining a deeper understanding of these patterns offers valuable insights into the mechanisms driving early cerebellar development. Further research is essential to fully grasp the implications of these complex activity in shaping cerebellar circuits and ultimately influencing cerebellar function.