BackgroundPsychosocial interventions for autistic adults remain limited. This study evaluated the implementation feasibility and potential clinical effectiveness of a manualized group psychotherapy program delivered under routine care conditions.MethodsData from 115 autistic adults who completed the program in routine outpatient care were analyzed. Outcomes included pre- to post-intervention changes in social responsiveness as primary outcome, as well as self-worth, depressive symptoms, and quality of life as secondary outcomes.ResultsOverall social responsiveness improved significantly from pre- to post-intervention. Significant post-intervention improvements were further detected for self-worth and depressive symptoms, while quality of life showed no significant change.DiscussionThe findings indicate that the manualized group psychotherapy program seems to be feasible in routine clinical care and was associated with improvements in social functioning, self-worth, and depressive symptoms, suggesting preliminary clinical effectiveness. However, randomized controlled trials are warranted to further establish efficacy.