ABSTRACT Objective Research suggests that combining the trauma-specific elements with a strong alliance helps optimize treatment outcomes in Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) for youth. Building on this, we investigate whether more positive and less negative involvement behaviors during trauma narration are associated with a stronger alliance and predict fewer posttraumatic stress symptoms (PTSS). Method Participants were 65 youth (M age = 15.5, SD = 2.2; 77% girls) receiving TF-CBT. Both youth self-report (Child PTSD Symptom Scale and Therapeutic Alliance Scale for Children) and observer ratings (Client Involvement Rating Scale) were used, and relationships were investigated with correlations and regression analyses. Results The positive involvement behaviors demonstration of treatment understanding and self-disclosure predicted fewer PTSS but were not associated with the alliance – while initiation of discussions and showing enthusiasm predicted more PTSS but were associated with a stronger alliance. The negative involvement behaviors passivity and avoidance did not predict PTSS but were negatively associated with the alliance. Conclusion The relationships between traumatized youths’ positive and negative involvement behaviors, alliance and PTSS outcomes appear mixed. The combination of a clear understanding of why processing the trauma can be helpful, more trauma-related self-disclosure and a stronger alliance seem favorable for alleviating PTSS. Trial registration: ClinicalTrials.gov identifier: NCT00635752..