Tight regulation of calcium (Ca(2+)) dynamics is critical for all neurons. Ca(2+) 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 Ca(2+) 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 Ca(2+) homeostasis in cerebellar microcircuits. This special issue covers recent advances in Ca(2+) signaling and imaging, and highlights the importance of spatiotemporal compartmentalization underlying Ca(2+) dynamics. Sorting out the pieces of the puzzle of homeostatic regulation of Ca(2+) remains an instrumental step to start rational therapies of Ca(2+) deregulation.