When cognitive behaviour therapy emerged in 1950s, driven by the work of Albert Ellis and Aaron Beck, basic behaviour principles were largely sidelined in clinical psychology curricula. Issues in cognition became the focus of case conceptualization and intervention planning for most therapists. But as the new "third-wave" behaviour therapies begin to address weaknesses in the traditional cognitive behavioural models - principally the modest effectiveness of thought stopping and cognitive restructuring techniques - basic behaviour principles are once again attracting the interest of front-line clinicians. Many of today's clinicians, though, received their training during the years in which classical behaviourism was not a major part of clinical education. In order to make the best use of the new contextual behaviourism, they need to revisit basic behavioural principles from a practical angle.This book addresses this need. "The ABCs of Human Behavior" offers practicing clinicians a practical introduction to the basics of modern behavioural psychology. The book focuses both on the classical principles of learning as well as more recent developments that explain language and cognition in behavioural and contextual terms. Practical and easy to read, the book walks clinicians through both common sense and clinical examples that help them learn to use behavioural principles to observe, explain, and influence behaviour in a therapeutic setting.