We study the effects of a decrease in college tuition on college application and enrollment behavior. Specifically, we use student-level data to analyze a Colorado law that granted in-state tuition to undocumented students residing in Colorado. We find an increase in the credit hours and persistence of newly enrolled and likely undocumented students. We do not find evidence of changes in the persistence or credit hours of continuing students. Leveraging application-level data, we show suggestive evidence that the policy induced more students to enroll in college through an increase in applications, rather than an increase in the acceptance rate or the enrollment rate.