The association between therapist internal relational models, professional self-doubt, and coping strategies and the process and outcome of psychotherapy

<b>Objective:</b> This study investigated whether therapists' level of professional self-doubt (PSD), in interaction with their internal relational models (i.e., their self-affiliation or attachment style), their experience level, and their professional coping strategies, impacted the alliance and symptom change in therapy.<b>Methods:</b> 555 clients (<i>M</i>_age = 42.8 years, 72.4% female) received individual psychotherapy from 54 psychologists. Associations between PSD, self-affiliation (in general and at its worst), avoidant and anxious attachment, years of experience, and constructive and avoidant-rejecting coping as predictors and moderators, and alliance or symptom change as outcomes, were analyzed using multilevel growth modeling.<b>Results</b> No direct effects of PSD, and no moderated effects between PSD and the therapist's internal relational models were found. However, higher PSD and more practice experience predicted steeper alliance growth in therapy, and higher PSD and more avoidant-rejecting coping predicted lower mid-therapy symptom levels.<b>Conclusion:</b> PSD generally did not exert a strong influence on the psychotherapy process and outcome. However, the significant interactions between PSD and experience level and avoidant-rejecting coping suggest that PSD may relate to alliance change amongst the most seasoned practitioners or could buffer against the negative effects of more avoidant therapist behaviors. These preliminary findings may inform future research on PSD.<b>Trial registration:</b> ClinicalTrials.gov identifier: NCT05630560..