The wide gap between science and practice in psychotherapy is due in part to the one-way direction that has mostly defined the connection between researchers and clinicians, with researchers generating empirical knowledge with the hope that practitioners will implement it in their working environment. This traditional approach has not been optimal in addressing the day-to-day concerns of clinicians, or in providing easily generalizable practice guidelines in clinical routine. This book offers an alternative approach to psychotherapy research, based on a partnership between clinicians and researchers in different aspects of the decision, design, implementation, and dissemination of studies conducted in day-to-day practice. More specifically, it describes how to conduct practice-oriented research (POR) by presenting studies and lessons learned (in terms of obstacles faced, strategies used to overcome problems, benefits earned, and general recommendations) by eleven groups of who have been involved in POR in different settings around the world. The book provides tools to help clinicians be active participants in conducting clinically relevant studies, and set the agenda for future research. It seeks to foster collaboration between researchers and practitioners, generating knowledge that can improve our understanding of the process of change and the impact of psychotherapy. This book was originally published as a special issue of Psychotherapy Research.