Global mental health has emerged in recent years as a field of research, advocacy, and practice that is concerned with improving the mental health of populations and reducing inequity in the global burden of mental illness. Because these challenges are multi-faceted, global mental health has been marked from its inception as a multi-disciplinary field, incorporating disciplines of psychiatry, psychology, epidemiology, health economics, anthropology, and implementation science. This chapter provides an overview of the emerging and dynamic field of global mental health. It starts with a brief history of the field, noting landmark publications and events. The chapter then introduces key areas of enquiry and action in global mental health, including epidemiology, mental health policy and services, intervention research, implementation science, qualitative research, instrument development, and economic evaluation. Finally, it concludes with reflections on critiques of the field and future directions.