A multivariate method for assessing cultural changes at stratified sites is proposed. The variables are technological properties of ceramics, and occurrences of various categories of fl int implements. The method is applied to stratigraphic sequences of Chalcolithic fortresses in the northwestern Caucasus dating to the late 5th- early 4th millennia BC: Meshoko and Yasenova Polyana. The properties of ceramics include hardness (assessed on the Mohs scale), wall thickness, and frequency of fragments tempered with calcium carbonate. For Meshoko, S.M. Ostashinsky's data on the occurrence of implements made of high-quality colored fl int, splintered pieces, and the total number of segments, points, inserts, scrapers, and perforators were used as well. Each parameter undergoes regular changes from the lower to the upper units of the sequence: ceramics progressively deteriorate, whereas fl int industry becomes more and more sophisticated. These changes occur in parallel. Data were subjected to principal component analysis. The fi rst principal component is regarded as a generalized measure of cultural change. The results support the view of the excavators: changes were caused by the interaction of two cultures differing in origin. The earlier culture, associated with the constructors of the Meshoko fortress, shows no local roots, and was evidently introduced from Transcaucasia. The one that replaced it was signifi cantly more archaic (a few copper tools notwithstanding), and reveals local Neolithic roots. It alone can be termed the culture of ceramics with interiorpunched node decoration. The ceramics of Yasenova Polyana, too, indicate cultural heterogeneity and two occupation stages; but cultural changes are more complicated there, probably because the site existed longer, and more than two cultural components were involved.