Abstract
In this paper we use individual-level census data on registered and practical nurses in the United States from 1950-70 to determine the effect that the switch from certification to licensure had on wages and participation in the registered and practical nurse professions. We examine these occupations to take advantage of a quasi-experiment afforded by the fact that, by the beginning of our sample, all states already had certification in place and some states already required a license. During the subsequent decade several states switched from certification to a mandatory licensing regime while others did not. Accordingly, we infer the effect of licensure in a differences-in-differences framework that uses states that did not change their regulatory regime as a control. Interestingly, we find that the shift from certification to mandatory licensing had little to no effect on the wages or the participation rate of practical and registered nurses.