Introduction: Blended cognitive behavior therapy (bCBT) is a treatment format that mixes internet-based modules with face-to-face sessions. It has the potential of making internet-based interventions more easily accessible and saving therapist time when delivering treatment for depression. The role of working alliance in this treatment format has not yet been thoroughly investigated. There is therefore a need to explore patient- and therapist rated alliance and the ability to predict change in depression during treatment using measurements of working alliance.

Methods: We used ratings of depression and alliance from 73 participants in a study on bCBT for depression (part of the E-COMPARED project). Data were analyzed using growth curve models.

Results: Both patient- and therapist rated alliance was high. The main finding was that therapist-rated alliance predicted change in depression scores during treatment.

Discussion: Working alliance can be established in bCBT, which is in line with previous research on face-to-face and internet-based treatment for depression. An interesting find was that therapist-rated alliance was of greater importance than patient-rated alliance when predicting change in depression during treatment. These results point towards therapist ratings of alliance being essential when delivering bCBT and conducting research on this method in the future.