The present paper comments on and extends the citation analysis of verbal operant publications based on Skinner's "Verbal Behavior" (1957) by Dymond, O'Hora, Whelan, and O'Donovan (2006). Variations in population parameters were evaluated for only those studies that Dymond et al. categorized as empirical. Preliminary results indicate that the majority of empirical research in the area of verbal behavior has been conducted with the younger developmentally disabled population and has focused on verbal operants from the introductory chapters of Skinner's book. It is clear that "Verbal Behavior" has influenced empirical research over the past 50 years. We believe, however, that there are many underdeveloped research areas originating from "Verbal Behavior" that have not yet been addressed. Suggestions for extended areas of research are provided. (Contains 2 tables and 2 figures.)