How does the cerebellum contribute to cognitive functions?

Over the past 70 years, neuroscience has gained a deep understanding of how the cerebellum supports basic motor functions. Anatomical, clinical, and neuroimaging studies, however, have also firmly established that the cerebellum holds an important role in cognition. Even though this topic has received considerable attention, we still do not know the exact nature of this contribution. This Unsolved Mystery reviews known facts about how the cerebellum contributes to cognition and identifies roadblocks that have prevented the development of a unified theory. Addressing these key questions should help the field develop the testable, falsifiable hypotheses that are needed to solve this intriguing question.