The cerebellum's role in cognitive skills was examined in a child (L.C.) with focal injury to the left cerebellum. Initial symptoms included aphasia and dysarthria. At 3 and 9 months post-injury, clinical neuropsychological tests revealed persistent psychomotor slowing as well as deficits in executive functions. Further cognitive testing at 13 and 16 months post-injury demonstrated that L.C. processed information from both the linguistic and nonlinguistic domains more slowly than age-, grade- and sex-matched controls. Notably, her linguistic processing was more than twice as slow as that of her peers, whereas her nonlinguistic processing was only approximately 20% slower. Within each domain the degree of cognitive slowing was approximately the same across diverse tasks. These results are consistent with the hypothesis of a cerebellar contribution to cognitive processing, particularly the processing of linguistic information. (JINS, 1998, 4, 491–501.)