This Handbook represents the first concerted effort to understand male mental health in a way that facilitates a positive step forward in both theory and treatment. An alarming number of men experience serious mental health issues, as demonstrated by high rates of suicide and violent offending. Despite these problems, the study of male psychology has either been overlooked, or viewed as a problem of defective masculinity. This handbook brings together experts from across the world to discuss men's mental health, from prenatal development, through childhood, adolescence, and fatherhood. Men and masculinity are explored from multiple perspectives including evolutionary, cross-cultural, cognitive, biological, developmental, and existential viewpoints, with a focus on practical suggestions and demonstrations of successful clinical work with men. Throughout, chapters question existing models of understanding and treating men's mental health and explore new approaches, theories and interventions. This definitive handbook encapsulates a new wave of positive theory and practice in the field of male psychology and will be of great value to professionals, academics, and those working with males through the lifespan in any sector related to male mental health and wellbeing. John Barry is a chartered psychologist and Associate Fellow of the British Psychological Society, Honorary Lecturer in Psychology at University College London, UK. He is co-founder of the Male Psychology Network, and the Male Psychology Section of the British Psychological Society. Roger Kingerlee is a consultant clinical psychologist and EMDR consultant at the Norfolk and Suffolk NHS Foundation Trust. Dr Kingerlee specialises in male and veteran psychologies and complex trauma. He is co-writer of the Veterans' Stabilisation Programme with The Walnut Tree Project, and a member of the Male Psychology Network. Martin Seager is a consultant clinical psychologist with the UK charity Change, Grow, Live. He spent over 30 years as a senior clinician, supervisor and manager in the NHS. He is a writer, lecturer, broadcaster and activist in the mental health field and co-founder of the Male Psychology Network, and the Male Psychology Section of the British Psychological Society. Luke Sullivan is a clinical psychologist. He is the founder of Men's Minds Matter, and also works for South London and Maudsley NHS Foundation Trust, specialising in psychological crisis interventions for people at risk of suicide. He is a committee member of the National Suicide Prevention Alliance and co-founder of the BPS Male Psychology Section.