Economic theories suggest that work behavior of public and nonprofit employees should resemble one another closely, owing to the lack of profit incentives and managerial or owner oversight of work. However, empirical descriptions of public and nonprofit workers imply that these work forces differ in many ways. One easily conceptualized but nonetheless crucial test of possible differences is level of work activity in the respective organizational settings. This research compares work hours reported in state public and nonprofit organizations by asking: Are there differences between time spent working in public and nonprofit organizations and, if so, what are the determinants of managers’ work hours? The study is based on questionnaire data from the National Administrative Studies Project-III. The analytical approach employs ordinary least squares regression. Factors examined in determining work hours include job histories, and perceptions of the organization and fellow employees. Results indicate that managers in the nonprofit sector tend to work longer hours compared to state managers and that work hours are mitigated by external organizational ties, perceptions, and work histories.