Research on psychotherapy integration: building on the past, looking to the future

Integration has become an important and influential movement within psychotherapy practice, reflected by the fact that many treatment providers now identify as integrative. However, integration has not had as great an influence on psychotherapy research. The goal of this paper is to highlight the growing body of research on psychotherapy integration, and to identify future directions for research that may strengthen the integration movement as well as the field of psychotherapy as a whole. We first summarize the past 25 years of research on integration, with a focus on four approaches to integration: theoretical integration, technical eclectic, common factors, and assimilative integration. Next, we identify directions of research within these four areas that could strengthen and support integrative practice. We then propose ways in which the perspective of integrationists could contribute to psychotherapy research in the critical areas of harmful effects, therapist effects, practice-oriented research, and training. We end this paper by suggesting that a greater collaboration between integrationists and psychotherapy researchers will help to create a unified landscape of knowledge and action that will benefit all participants and advance the field.