The cerebellum has traditionally been seen primarily to coordinate voluntary movement, but evidence is accumulating that it may play a role in cognition and behavior as well. This is a selective review of studies assessing potential cognitive deficits and personality changes associated with cerebellar disease. Preliminary studies of the role of the cerebellum in schizophrenia, dementia, and other psychiatric disorders are also discussed. Efforts to understand the neurological substrates of behavior should consider the role of the cerebellum.