This book focuses on practical insights gained from research on ACT in targeted populations and settings. Leading experts share how ACT has been tailored and refined to best address problems including depression, anxiety, psychosis, health-related conditions, burnout, adolescent mental health, and insomnia. This book focuses on lessons learned from years of researching and refining ACT in specific areas, including those that have not been covered in similar books with topics such as autistic adults, caregivers, and audiological conditions. This book also provides important developments in assessment, case conceptualization, and treatment at different levels of care. Highly relevant to practitioners and researchers alike, this volume offers an up-to-date picture of ACT and its expanding potential.

Optimizing ACT is an important contribution to the ongoing evolution of Acceptance and Commitment Therapy. Levin and Twohig have brought together some of leading ACT experts to show how ACT continues to grow—not by abandoning its core, but by deepening and refining it through research and practical extension. This volume offers clinicians a clear, evidence-informed picture of where ACT is heading: toward ever more precise, flexible, and person-centered system of intervention.
Steven C. Hayes, PhD, University of Nevada, Reno

This edited volume by Drs. Levin and Twohig spans impressive ground that is vital to understanding and applying ACT in clinical practice. Early chapters provide an outstanding overview of ACT, how to assess key processes, and tailor to individual clients, whereas the latter chapters showcase applications to diverse clinical problems. Even after using ACT for more than 20 years, every chapter taught me something new!
Joanna Arch, PhD, University of Colorado Boulder

There is no other book like it. In this volume Levin and Twohig bring together an entirely up to date perspective on how to conceive and deliver ACT and marry this perspective with lessons learned around the unique needs and contexts of specific populations and health conditions. With chapters from top researchers and clinicians in their specific topic areas, this volume is exactly what treatment providers need today, strategies and tools that are context-sensitive, increasingly personalizable, and highly practical.
Lance M McCracken, PhD, Uppsala University

Michael E. Levin, Ph.D. is a Professor in the Department of Psychology at Utah State University where he co-directs the ACT Research Group. His research focuses on the development, evaluation, and implementation of digital ACT interventions for a wide range of problem areas including depression, anxiety, obsessive compulsive and related disorders, and chronic health conditions. He has conducted over 50 clinical trials evaluating digital ACT programs through ongoing federal and foundation funding over the past 15 years. This research has led to the dissemination of ACT Guide, a publicly available suite of digital ACT self-help programs.

Michael P. Twohig, Ph.D. is a psychologist and Professor at Utah State University, where he co-runs the ACT Research Group. He is past-President of the Association of Contextual Behavioral Science and winner of the 2025 D. Wynn Thorne career research award. His research focuses on the use of ACT across a variety of clinical presentations with an emphasis on obsessive compulsive and related disorders. He has published over 250 peer-reviewed papers, many book chapters, and 13 books. In 2022, 2024, and 2025 he was rated as the most productive author on ACT in the world.