Abstract Fifteen stutterers, primarily children, who visited the Medical Pedagogical Department at the University of Blagoevgrad were evaluated for a variety of criteria used in Bulgaria to differentiate cluttering, stuttering, and mixed cluttering and stuttering. The same battery of tests was administered to all subjects. Based on these criteria, five subjects were diagnosed as clutterers, six as stutterers, and four as mixed. Daly's (1992–1993) Checklist for Possible Cluttering, Experimental Edition was also utilized to classify the subjects. Differences between the differential diagnostic criteria used by Bulgarian logopedists and other authors are discussed.