Occupational health psychology (OHP) is a cross-disciplinary subspecialty within psychology. OHP derives from two disciplines within applied psychology, health psychology and industrial/organizational psychology. OHP is also linked to disciplines outside of psychology, such as occupational medicine and public health. The discipline has roots in eighteenth, nineteenth, and twentieth century thinkers, including Adam Smith, Friedrich Engels, Karl Marx, Émile Durkheim, and Max Weber. These thinkers were concerned with the impact of the organization of work and the business cycle on human life. Later research by Elton Mayo, Marie Jahoda, Walter B. Cannon, Hans Selye, and investigators at the University of Michigan’s Institute for Social Research, the Tavistock Institute in London, and the Stress Research Laboratory (now the Stress Research Institute) in Stockholm laid a foundation for OHP before the term was coined. While health psychology has largely been concerned with influences outside the domain of work that affect health and health behaviors, OHP emerged as a discipline that is concerned with understanding the nature of the impact of psychosocial working conditions on the physical and mental health and well-being of workers and their families. Examples of psychosocial working conditions include: (a) how much decision latitude a worker has, (b) psychological workload, and (c) the extent to which there is an imbalance between a worker’s effort, on one hand, and the tangible and intangible rewards the worker gets from the job, on the other. Knowledge obtained from such research is used to develop interventions designed to protect and enhance the health of workers, while maintaining organizational productivity. OHP is also concerned with occupational safety and accident prevention, the impact of unemployment and job insecurity on mental and physical health, the prevention of violence and psychological aggression at the workplace, and identifying factors that enhance work-family balance.