This paper examines the effects of occupational licensing on the quality of Certified Public Accountants (CPAs), especially the staggered adoption of the 150-hour rule, which increases the educational requirements for a CPA license. The analysis shows that the rule decreases the number of entrants into the profession, reducing both low- and high-quality candidates. Labor market proxies for quality find no difference between 150-hour rule CPAs and the rest. Moreover, rule CPAs exit public accounting at similar rates and have comparable writing quality to their non-rule counterparts. Overall, these findings are consistent with the theoretical argument that increases in licensing requirements restrict the supply of entrants and do little to improve quality in the labor market.