Inappropriate verbal behavior that is labeled "psychotic" is often described as insensitive to environmental contingencies. The purpose of the current study was to establish different classes of rational or appropriate verbal behavior in a woman with developmental disabilities and evaluate the effects on her psychotic or aberrant vocal verbal behavior. Similar to a previous study (Arntzen, Ro Tonnessen, & Brouwer, 2006), the results of the current study suggested that the procedure helped to establish a repertoire of appropriate functional vocal verbal behavior in the participant. Overall, the results suggested the effectiveness of an intervention based on training various classes of verbal behavior in decreasing aberrant verbal behavior. (Contains 2 tables and 2 figures.)