Substance use disorder (SUD) is a serious disorder with severe consequences for the individual, the family and for society. Comorbidity is common in the SUD population and the diversity of the disorder calls for a multiplicity of treatment options.The overall aim of this thesis was to explore the role of affects in psychotherapy for SUD. Further aims were to investigate affect-focused therapeutic orientations, demonstrate the importance of common factors and evaluate a measure of affect phobia.In Study I a naturalistic design was employed to examine how the discrepancy between patients' expectations and experience of psychotherapy related to alliance in 41 patients: 24 in individual therapy and 17 in group. An additional analysis concerned whether different dimensions of role expectations predicted retention in psychotherapy. Study II was the first psychometric evaluation of the Affect phobia test -a test developed to screen the ability to experience, express and regulate emotions. Data were collected from two samples: A clinical sample of 82 patients with depression and/or anxiety participating in a randomized controlled trial of Internet-based affectfocused treatment, and a university student sample of 197 students. Data analysed included internal consistency, test-retest reliability, factor analysis and calculation of an empirical cut-off. Study III focused on the feasibility of individual 10 week Affect Phobia Therapy (APT) for patients diagnosed with mild to moderate alcohol use disorder (AUD) and problematic affective avoidance in a nonconcurrent multiple baseline design. Study IV comprised an evaluation of the feasibility and preliminary effectiveness of APT adapted to a structured group format for patients (n=22) with comorbid substance use disorder and ADHD with core features of affective avoidance/emotion dysregulation in an open design.In Study I an overall discrepancy between role expectations and experiences was significantly related to a lower level of therapeutic alliance in group therapy. This relationship was not found in individual therapy. Expectations prior to psychotherapy characterized by defensiveness correlated negatively with therapy retention, even when controlling for waiting time for therapy. In Study II the internal consistency for the total score on the Affect phobia test was satisfactory but it was not for the affective domains, Anger/Assertion, Sadness/Grief, and Attachment/Closeness. Test retest reliability was satisfactory. The exploratory factor analysis resulted in a six-factor solution and only moderately matched the test´s original affective domains. An empirical cutoff between the clinical and the university student sample were calculated -3 -and yielded a cut-off of 72 points. In Study III patients reported no adverse events due to the treatment and finished the whole study period. The patients had different trajectories of alcohol consumption and craving and the hypothesis that heavy episodic drinking would subside during the time in therapy did not hold true. In ...