Elaborating the assimilation model: Introduction to a special section on case studies of setbacks within sessions and therapeutic collaboration.

This article introduces a Special Section of case studies that focus on therapeutic collaboration and setbacks in the process of assimilation with the aim of contributing to the evolution of the assimilation model of therapeutic change. The first study examined setbacks in two depression cases (a good vs. a poor outcome) treated with emotion-focused therapy. The second article traced how therapist activities and positions toward internal voices were associated with setbacks in a case treated with linguistic therapy of evaluation. The third article studied contributions of therapeutic collaboration for both advances and setbacks in assimilation in two contrasting cases treated with emotion-focused therapy. The fourth and final article analyzed the therapeutic collaboration in episodes of ambivalence in two cases of narrative therapy (one good outcome, one poor outcome) reflecting on the implications for the assimilation model's perspective on the therapeutic relationship. This Introduction concludes by offering some suggestions for theory-building within the assimilation model.