SARAH CASSIDY is an educational, child and adolescent psychologist who specialises in the assessment and treatment of learning and emotional/behavioural difficulties. She is the Founder and Director of the Smithsfield Clinic, a private practice for young people and their families using largely ACT (Acceptance and Commitment Therapy) and RFT (Relational Frame Theory) treatment methods. She lectures in Psychology at Maynooth University and trains ACT therapists throughout Ireland. LISA COYNE is the Founder and Senior Clinical Consultant of the McLean OCD Institute for Children and Adolescents at McLean Hospital, Massachusetts, and an Assistant Professor at Harvard Medical School. She is the Founder and Executive Director of the New England Center for OCD and Anxiety, a Past President of the Association of Contextual Behavioral Science (ACBS) and the author of several books.