Huntington's Disease (HD) has been described as one example of a "subcortical" dementia, characterized by slowed cognitive processing and impairment of memory. We examined the relationship between slowed cognitive processing and memory impairment as a function of disease progression in patients with HD. Results from three experiments suggest that in the early stages of HD there is slowed cognition with intact memory acquisition and retrieval processes. In later stages, cognition is further slowed and specific impairments of memory become evident. Thus, memory impairment in HD would appear to change qualitatively with progression of the disease.