Tamar D. Black, PhD, is an educational and developmental psychologist in Melbourne, Victoria, Australia. She is a school psychologist and runs a private practice, working with children, adolescents and parents. She has extensive experience providing clinical supervision to early career and highly experienced psychologists. She also provides training in ACT to clinicians and teachers in using ACT with children and adolescents, and using ACT in schools.

Foreword writer Russ Harris is a therapist and coach, and was a general practitioner before being introduced to ACT. Russ is a world-renowned ACT trainer, and is the author of ACT Made Simple, Trauma Focused ACT, Getting Unstuck in ACT, ACT Questions & Answers, The Happiness Trap, The Reality Slap, The Confidence Gap and ACT with Love.