Introduction: Alliance ruptures constitute a high risk of premature treatment termination and poor psychotherapy outcome. The Alliance-Focused Training (AFT) is a promising transtheoretical approach to enhance therapists` skills in dealing with alliance ruptures. Methods and analysis: To evaluate the effectiveness of Modified AFT with doubling (MAFT-D), a randomized, patient and evaluator-blinded, multicenter trial was designed comparing MAFT-D (delivered to trainee therapists and supervisors) and psychotherapy training/ treatment as usual (TAU) for therapists (n=120) and their patients with depressive disorders (n=240). A total of 16 cooperating centers, each offering either cognitive-behavioral or psychodynamic psychotherapy training, will contribute to recruitment. Stratifcation by center (both for therapists and patients) and hence therapeutic approach (cognitive-behavioral vs. psychodynamic psychotherapies), and by comorbid personality disorder (yes vs. no, for patients) will be carried out. The two hierarchically ordered primary hypotheses are: In MAFT-D compared to TAU, a stronger reduction of depressive symptoms and a lower rate of patient dropout is expected from baseline to 20 weeks after baseline. Follow-up assessments are planned at 35 weeks, 20 months, and 36 months post-baseline to evaluate the persistence of effects. Secondary patient- and therapist-related outcomes as well as predictors, moderators, and mediators of change will be investigated. Mixed models with repeated measures will be used for the primary analyses. Ethics and dissemination: Ethical approvals were obtained by the institutional Ethics review board of the main study center as well as by review boards in each federal state where one or more cooperating centers are located (secondary votes). Following the Consolidated Standards of Reporting Trials statement for non-pharmacological trials, results will be reported in peer-reviewed scientific journals and disseminated to patient organizations and media. Trial registration number DRKS00014842 (German Clinical Trial Register).

The authors have declared no competing interest.

DRKS00014842 (German Clinical Trial Register)

This study is funded by the German Research Foundation (DFG); project number: 504346851; GU 1564/6-1; Principal Investigator: Antje Gumz).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethics Committee of the Psychologische Hochschule Berlin gave ethical approval for this work (EK2024/11). Additionally, we obtained secondary votes in each federal state where one or more study centers are located.

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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On request, anonymized raw data will be made available to scientific colleagues after finishing the trial. During the publication process, relevant trial data will be uploaded to the Dryad Digital Repository.