Mark Webster is a registered psychotherapist with the United Kingdom Council for Psychotherapy (UKCP). Following a first career in the computer industry, he worked for ten years at a specialist personality disorder clinic in the National Health Service (NHS). His involvement in third-wave cognitive behavioral therapy (CBT) began with dialectical behavior therapy (DBT) in 1997, which led to an early interest in ACT. Webster has been an ACT trainer since 2002, and currently runs his own business specializing in acceptance and mindfulness therapies. In 2005, he founded the ACT special interest group within the British Association for Behavioural and Cognitive Psychotherapies (BABCP). In 2008, with Kevin Polk, he created the ACT Matrix, a very user-friendly way of delivering ACT in a group setting. Webster’s main interest is in finding ways to make ACT more widely available outside of traditional mental health settings. He has recently founded a community interest company called ACT Peer Recovery CIC to develop peer recovery in addiction and mental health. In addition to offering training in mental health, he regularly conducts ACT workshops for physical health practitioners, including nurses, physiotherapists, and occupational therapists. Webster has been practicing mindfulness for over twenty-five years, and is current chair of the UKCP’s Cognitive Psychotherapies College.