Tight regulation of calcium (Ca²⁺) dynamics is critical for all neurons. Ca²⁺ is a major mediator of cellular excitability, synaptic plasticity, and regulation of transcription, amongst others. Recent years have seen major developments in terms of understanding the roles of Ca²⁺ signals in the cerebellar circuitry, especially for Purkinje neurons and granule cells. The unique morphology of Purkinje neurons serves as a platform to unravel the secrets of Ca²⁺ homeostasis in cerebellar microcircuits. This special issue covers recent advances in Ca²⁺ signaling and imaging, and highlights the importance of spatiotemporal compartmentalization underlying Ca²⁺ dynamics. Sorting out the pieces of the puzzle of homeostatic regulation of Ca²⁺ remains an instrumental step to start rational therapies of Ca²⁺ deregulation.