A recent Dutch RCT investigating the effectiveness of the D(o)epression protocol (face-to-face) has shown that CBT was moderately effective compared to CAU. Despite this, some adolescents were not free of depressive symptoms at posttreatment, the drop-out was high, and it was hard to motivate patients to finish the treatment. Therefore, it seems important to develop an attractive and even more effective treatment for adolescents. The treatment protocol D(o)epression Blended is developed for treatment of depressive disorders in adolescents. Online interventions might be promising, but are only studied as preventive interventions and without face-to-face guidance by therapists. Therefore, the aim is to examine the effectiveness and costeffectiveness of D(o)epression Blended and compare it to D(o)epression face-to-face and CAU to contribute to evidence-based treatment of depressive adolescents in psychiatric care. Further, moderators, mediators, individual trajectories of change, expectations, and satisfaction in adolescents and therapists will be studied.