In accordance with social exchange theory, prominent streams of management research emphasize the importance of reciprocal exchange relationships between organizations and their employees. When employees perceive themselves as supported by the organization, they reciprocate with increased work motivation. However, we do not know how this knowledge can be developed into management initiatives that increase public employees’ perceived support, because severe endogeneity problems make it difficult to estimate the effect of organizational support on employee commitment outside the laboratory. We use a randomized field experiment involving more than 800 public employees to estimate the effect. We find no average effect of the organizational support treatment on the employees’ perceived organizational support. Yet, a subgroup analysis shows a positive treatment effect when the employees’ local front-line managers felt less supported prior to the intervention. We discuss the implications for theory and management practice. ©2012 by the Association for Public Policy Analysis and Management.