This paper outlines and discusses how the original theoretical framework about verbal behaviour was maintained and modified during past decades. This article has three purposes: a) to review and compare the analysis of the speaker's behaviour based on Skinner's analysis of verbal behaviour with the analysis of referential language interactions based on Kantor's Psychological Linguistics; b) to discuss some of the major outcomes achieved with such approaches in the establishment of verbal repertoires in individuals with moderate and severe disabilities; e) to describe some of the major challenges still to be accomplished with such approaches, and raise questions for future research. A great deal of clinical and experimental work based on Skinner's analysis and classification on verbal behaviour has focused on establishing functional verbal repertoires that are used across various setting and situations by mentally retarded and developmentally disabled people. Such approach have often focused on very structured methods, sometimes employing one-to-one training in specific stimulus contexts with various powerful reinforcers. As a result, persons have not been trained to respond to the type and variety of stimuli and controlling conditions found in their typical non-training environments. Another line of research has involved the successful training of more complex tacting, manding, and intraverbal responses in a variety of more natural settings and situations. Such work, while has gradually involved a careful functional analysis of contextual and developmental factors including motivational variables, subjects interest and preference, has produced a variety of techniques .and teaching procedure highly effective in identifying multiple control and, consequently, in changing verbal repertoire. Such techniques have often resulted in more spontaneous verbal performance. While progress continue to be made, it seems useful to develop more comprehensive approaches to analysing and assessing contextually relevant conditions. What is needed is a strategy for more careful analysis of the full range of controlling variables that should set the occasion for verbal responding. Such an analysis include people, objects as well as relevant motivative variables (establishing operations). In order to identifying preferences and reinforcer effectiveness, systematic assessment methods are developed. Much of experimental efforts in this research area suggest that accurate assessment procedures can be used to predict the relative reinforcing value of various stimuli, which, in turn, may help to improve programs for clients with severe to profound disabilities. A great deal of progress has been made in the area of explaining and establishing verbal repertoires; however, the complexity of stimulus control relationships in verbal behaviour will surely provide a challenge to further advancement. Thus, these studies have improved scientific knowledge about behavioural function serving as excellent examples of how basic and applied research are closely interrelated, and bringing considerable support for the claim that the applied behaviour analysis has held faith to its original promise.Questo articolo delinea sía la struttura teorice originale relativa al comportamento verbale sia le modifiche ad essa apportate negli ultimi decenni ponendosi trei obiettivi: a) confrontare l'analisi del comportamento verbale di Skinner con la linguistica psicológica di Kantor; b) discutere i risultati raggiunti nel trattamento del repertorio verbal e in soggetti con disabilitá dello sviluppo; c) descrivere alcune sfide che questi approcci dovranno fronteggiare e, contemporaneamente, sollevare alcuni quesiti fondamentali per la ricerca futura. Molto lavoro clinico e sperimentale basato sull'analisi e la classificazione di Skinner del comportamento verbale ha posta attenzione sui repertori funzionali verbali usati in varie situazioni da soggetti con ritardo mentale e con disabilitá dello sviluppo. Tale lavoro ha incluso gradualmente l'analisi funzionale del fattori del contesto e dello sviluppo, come le variabili motivazionali, I'interesse e la preferenza del soggerto, ed ha prodotto una varietá di tecniche e procedure molto efficaci nell' identificare il controllo múltiplo e, di conseguenza, nel modificare determinati repertori verbali. Questi studi hanno migliorato la conoscenza scientifica sulle funzioni comportamentali esempliticando in modo eccellente I'interconnessione tra ricerca di base e ricerca applicata e sostenendo I'idea che l'analisi applicata del comportamento ha tenuto fede alla sua promessa originale.