This paper presents some preliminary results from a different approach to research on psychotherapeutic processes. As activity in psychotherapy is predominantly verbal, we propose a scientific study of therapists' verbal behavior from a behaviorist perspective. Data were obtained through observational analysis of the recordings of 16 clinical sessions involving 4 cases, all of which based on individual cognitive-behavioral therapy with adults, in the framework of private clinical practice in Spain. The analysis used a previously validated system of categories and The Observer XT software to register and code data. A descriptive analysis enabled us to identify several patterns of psychologists' verbal behavior, irrespective of the therapist and/or the case analyzed. Notable differences were also observed in clinicians' performance, which raises important questions about potential variables associated with therapeutic change. Finally, we discuss the strengths and weaknesses of the present research agenda, the development of which should lead to a fuller understanding of the psychotherapeutic phenomenon.