Occupational scientists must synthesise and apply knowledge generated within related disciplines to ensure the continued development of the discipline. This paper reviews the evidence available to occupational scientists on human happiness. This body of knowledge can be utilised by occupational scientists to better understand the subjective experience of occupational engagement. Two key philosophical traditions in happiness studies, hedonism and eudaimonia, are presented and theories of human happiness, including setpoint theory, are described. A number of thematic areas of research on human happiness are reviewed. The relationships between happiness and health, living situation, personal goals, work, volunteering, flow, religiosity and relationships are reviewed. The reviewed studies underscore the centrality of occupation to current understandings of human happiness. © 2012 The Journal of Occupational Science Incorporated.