Nurses employed in hospitals realize a large wage advantage relative to nurses employed elsewhere. This paper examines alternative sources of the hospital premium, a topic of some interest given the current shifting of medical care out of hospitals. Whereas cross-sectional estimates indicate a hospital RN wage advantage of roughly 20 percent, longitudinal analysis suggests that a third to a half of the advantage is due to unmeasured worker ability. The remainder is likely to reflect compensating differentials for hospital disamenities. We further probe possible sources of the RN hospital premium by examining the receipt of fringe benefits, differences in cognitive ability as measured by AFQT test scores, differences in the quality of experience, the role of labor unions and rents, earnings on second jobs, and the magnitude of wage differentials associated with work shift.The authors appreciate helpful suggestions from Marjorie Baldwin, Marie Cowart, Gary Fournier, David Macpherson, Lester Zeager, and an anonymous referee. The CPS data sets used in this paper were developed with the assistance of David Macpherson.