Adults spend more time working than in any other activity. Therefore, it may not be surprising that work is a significant threat to health for many, leading to thousands of deaths and millions of injuries each year just in the United States. Although work is frequently the cause of many health problems, it also is the source of solutions to some of those same safety and health concerns. Occupational health psychology arose as a scientific discipline with the goal of studying occupational health from a behavioural science perspective in order to understand better how to protect and promote worker safety, health and well-being. In this contribution, we define the field of occupational health psychology, review the general categories of health outcomes of interest to the discipline, discuss examples of some interventions and influential factors in occupational health, and describe the newly emerging Total Worker Health™ program.