This paper examines the effect of tuition subsidy in the form of in-state tuition to undocumented students on the education of noncitizen Mexican young adults. The policy is found to be associated with a 2.5 percentage point increase in college enrollment (base mean = 8%), a 3.7 percentage point increase in the proportion of students with at least some college education (base mean = 10%), and a 1.3 percentage point increase in the proportion with at least an associate degree (base mean = 4%). These results are robust to a variety of specifications. When the analysis is restricted to samples more likely to be affected by the policy, point estimates become larger. The study finds no evidence that in-state tuition policy for the undocumented adversely affects the educational outcomes of natives. © 2008 by the Association for Public Policy Analysis and Management.