A 30-item questionnaire concerned with signs and symptoms of cognitive decline was completed by a relative or caregiver for each of 115 elderly patients seen in the gerontology outpatient clinic of our institution. Twelve different preliminary scale values were calculated to locate each of the 30 clinical manifestations along a continuum of increasing severity. Principal components analysis was then used to combine the 12 preliminary indices into a single composite scale that more reliably represents distances between the 30 clinical manifestations. The scale scores for the clinical manifestations were observed to cluster into relatively discrete groups, suggesting naturally occurring stages or phases. Objective cluster analysis methods further suggested the presence of distinct thresholds for occurrence of new impairments along the cognitive decline continuum. Utility of the empirically derived scale values in staging the course of primary degenerative dementia is suggested.