The positive benefits of physical activity for physical and mental health are now widely acknowledged, yet levels of physical inactivity continue to increase throughout the developed world. Understanding the psychology of physical activity has therefore become an important concern for scientists, health professionals and policy-makers alike. Psychology of Physical Activity is a comprehensive and in-depth introduction to the fundamentals of exercise psychology, from theories of motivation and adherence to the design of successful interventions for increasing participation. Now in a fully revised, updated and expanded third edition, Psychology of Physical Activity is still the only textbook to offer a full survey of the evidence-base for theory and practice in exercise psychology, and the only textbook that explains how to interpret the quality of the research evidence. With international cases, examples and data included throughout, the book also provides a thoroughly detailed examination of the relationship between physical activity and mental health. A full companion website offers useful features to help students and lecturers get the most out of the book during their course, including multiple-choice revision questions, PowerPoint slides and a test bank of additional learning activities. Psychology of Physical Activity is the most authoritative, engaging and up-to-date introduction to exercise psychology currently available. It is essential reading for all students working in exercise and health sciences.