Work motivation is a topic of crucial importance to the success of organizations and societies and the well-being of individuals. We organize the work motivation literature over the last century using a meta-framework that clusters theories, findings, and advances in the field according to their primary focus on (a) motives, traits, and motivation orientations (content); (b) features of the job, work role, and broader environment (context); or (c) the mechanisms and processes involved in choice and striving (process). Our integrative review reveals major achievements in the field, including more precise mapping of the psychological inputs and operations involved in motivation and broadened conceptions of the work environment. Cross-cutting trends over the last century include the primacy of goals, the importance of goal striving processes, and a more nuanced conceptualization of work motivation as a dynamic, goal-directed, resource allocation process that unfolds over the related variables of time, experience, and place. Across the field, advances in methodology and measurement have improved the match between theory and research. Ten promising directions for future research are described and field experiments are suggested as a useful means of bridging the research-practice gap.