Empirical research has established that both individual and group psychotherapy is effective for a broad range of psychiatric disorders, but less is known about the processes associated with positive treatment outcomes. The aim of the present thesis was to examine the individual and combined contribution of two essential aspects of the Generic Model of Psychotherapy to outcome, namely the therapeutic bond (therapeutic alliance; group climate) and therapist interventions (homework assignments; transference work). Data was taken from two previously published randomized controlled trials. The first trial examined the effectiveness of cognitive behavioral group therapy (CBGT) for patients with comorbid disorders, whereas the second trial examined the effectiveness of short-term dynamic psychotherapy (STDP) and cognitive therapy (CT) for patients with cluster C personality disorders. Paper I found support for the use of a trans-theoretical measure of group climate as a predictor of long-term followup outcome in CBGT for comorbid disorders, particularly the dimension of engagement. In paper II, early ratings of therapist competence in assigning homework was found to predict both mid- and post treatment outcomes in CT with cluster C personality disorders. The use of homework assignments was not observable in STDP. This finding emphasizes the quality of homework assignments as an important and measurable therapist skill essential for treatment outcome, at least in CT. Paper III reported that a stronger emphasis on transference work, especially in the context of a weak therapeutic alliance, was associated with a smaller reduction in interpersonal problems at treatment termination in STDP and CT with cluster C personality disorders. The findings demonstrate the “risks” involved in having a stronger emphasis on transference work, especially in the context of a weak therapeutic alliance early in treatment. The results add to the importance of examining the contribution of the therapeutic bond, therapist interventions and their interaction to outcome in psychotherapy, and have noteworthy clinical implications for practicing therapists.