Objective: It has been demonstrated that patient perspective on alliance can predict subsequent treatment outcome as reported by the therapist but not the other way around. This study aimed to investigate the circumstances in which therapists can provide estimations of alliance capable of predicting patient perceptions of subsequent session outcome. The study focused on 2 potential indicators: time in treatment and treatment efficacy. Method: Data of 107 treatment completers assigned to either cognitive-behavioral therapy or alliance focused therapy were analyzed. Data included session-to-session assessments of alliance and the session outcome measure across the 30 weeks of treatment as well as pretreatment to posttreatment assessments of treatment efficacy using the Symptom Checklist-90–Revised. An actor-partner interdependence model of longitudinal hierarchically nested data, disentangled for within- and between-patients effects, was used. The interactive effects of time and treatment efficacy and their combined effect were examined. Results: At the sample level, as expected, the therapist perspective of alliance did not significantly predict patient perception of subsequent session outcome, but significant interaction effects were detected. Therapists’ perspective on the alliance was a stronger predictor of patients’ perception of subsequent session outcome when therapy was more rather than less effective. This effect was evident mainly early in treatment, during which greater variability across dyads was found. Conclusions: Findings suggest that although therapists’ ratings of the alliance are not consistently predictive of patients’ rating of subsequent session outcome, they are better predictors in more than in less effective treatments.