In this chapter we decompose the neuronal circuits that connect the cerebellar cortex with other CNS structures. Some of the component cells are those of origin of afferents to the cerebellum that are located in the spinal cord and brainstem. These cells issue afferents known as mossy fibers, climbing fibers, and beaded fibers. Other component cells are the recipients of inhibitory signals from Purkinje cells, and they are located in cerebellar nuclei and selected brainstem nuclei. These precerebellar and postcerebellar cortex neurons, together with cerebellar cortical networks, constitute “global” neural systems that incorporate the cerebellum.