The 2-volume APA Handbook of Psychotherapy comprehensively presents the field based on the primary ways in which professionals practice psychotherapy and affect such practice through theory, research, and training. 50 authoritative chapters capture the most representative ways in which psychotherapists characterize the driving forces behind their foundational therapeutic approaches. Therapists may: Administer psychotherapy according to a specific theoretical orientation, applying this model across most patients and contexts Use a specific, "named" therapy to primarily treat patients suffering from a particular disorder Draw on research evidence to administer psychotherapy in a way that can include, but also transcend, specific theoretical orientations and disorder-specific interventions Generate data and draw on varied forms of research psychotherapy in a participant-driven and contextually responsive manner These chapters represent the latest thinking and evidence on the most relevant topics across the "big four" psychotherapy domains of theory, research, practice, and training. All four parts are written for researchers, practitioners, scholars, and trainers, with the major difference among the sections being their emphasis on, and order of, discussing the "big four" elements.