The issues of temporal coding and the temporal organization of activity have aroused a great deal of interest in sensory systems, cortex, thalamus, and hippocampus. Strangely, despite the important timing roles attributed to the cerebellum, little consideration has been given to the organization of activity within the cerebellar circuitry. In fact, there is evidence of a remarkable temporal patterning of activity in even the earliest cerebellar recordings. The evidence for the existence of high-frequency oscillations in the cerebellar cortex is reviewed and possible mechanisms are discussed; one involves the synchrony of parallel fiber inputs to Purkinje cells. It is shown how synchronous and oscillatory activity can enable extremely precise timing and also how they can maximize the information storage capacity of the cerebellar cortex.