This research described the process of first sessions of CBT for psychosis and reported on the development and validation of a new measure of affective response. It used the new measure to explore relationships between client and therapist affective response and therapy adherence, working alliance and empathy. Transcripts from first sessions of CBT were used to illustrate these relationships qualitatively. Study 1 used data from sixty two therapist/client dyads engaged in routine services and an ongoing controlled trial to develop and validate the new measure of affective response. Study 2 used data from only the controlled trial to explore and examine relationships between therapy processes. Audio-tapes from twenty five dyads were transcribed and rated on measures of adherence and working alliance The new measure of affective response demonstrated acceptable internal consistency for the total scale. Adaptations were made to the subscale structure and both scales demonstrated adequate internal consistency. Convergent validity with a measure of empathy was not demonstrated and test-retest reliability correlations were varied for the therapist scale and reasonable for the client scale. All sessions were adherent to the cognitive therapy manual used. Client and therapist affective response was predominantly positive, empathy ratings were high and the working alliance was good. No relationships were observed between affective response and working alliance or between client and therapist affective response. Increased negative affective response was associated with greater insight orientated techniques and session transcripts suggested this was because clients were unable to tolerate more active interventions and as a result this led to therapists experiencing greater negative affective responses. Study limitations are highlighted and future research recommendations are made, specifically the need to further validate the scale and examine affective response with both adherent and non-adherent therapy. Finally the clinical implications of the research are presented.