Acceptance and commitment therapy, or ACT (pronounced as a word rather than letters), is an emerging psychotherapeutic technique first developed into a complete system in the book Acceptance and Commitment Therapy by Steven Hayes, Kirk Strosahl, and Kelly Wilson.

ACT marks what some call a third wave in behavior therapy. To understand what this means, it helps to know that the first wave refers to traditional behavior therapy, which works to replace harmful behaviors with constructive ones through a learning principle called conditioning. Cognitive therapy, the second wave of behavior therapy, seeks to change problem behaviors by changing the thoughts that cause and perpetuate them.

In the third wave, behavior therapists have begun to explore traditionally nonclinical treatment techniques like acceptance, mindfulness, cognitive defusion, dialectics, values, spirituality, and relationship development. These therapies reexamine the causes and diagnoses of...

John P. Forsyth, PhD, is professor of psychology and director of the anxiety disorders research program at the University at Albany, SUNY. Forsyth is a highly sought-after speaker, acceptance and commitment therapy (ACT) workshop leader, and member of the teaching faculty at the Omega Institute for Holistic Studies, the Esalen Institute, and 1440 Multiversity. His teachings and writing focus on how to use ACT and mindfulness practices to alleviate suffering, awaken the human spirit, and cultivate well-being. He is coauthor of The Mindfulness and Acceptance Workbook for Anxiety.