This dissertation consists of three separate chapters, each of which investigates a unique policy in secondary and postsecondary education. The first chapter analyzes how banning standardized tests in college admissions would affect enrollment patterns and graduation rates in the United States. To conduct this analysis, I build an equilibrium model in which colleges rebalance their admissions criteria towards other measurements of students' human capital in the absence of standardized exam scores. The model allows for endogenous application decisions and human capital investments by high school students, while colleges adjust admissions thresholds to maximize their objectives. I find that banning the SAT has a negligible effect on the enrollment of under-represented minority (URM) students. Elite colleges are worse off after banning the SAT, as they enroll students with lower skills and see graduation rates drop by 3 pp, while completion rates rise at less selective schools. A separate policy that requires all students to take the exam raises college completion for URMs by 1.6 pp overall by helping schools to identify stronger students. The second chapter analyzes a long-running distance education program in Mexico. This chapter estimates marginal treatment effects (MTEs) for learning in math and Spanish in telesecundarias relative to traditional Mexican secondary schools using an empirical framework that allows for sorting on unobserved gains. The estimated MTEs reveal that school choice is not random and that the average student experiences significant improvements in both math and Spanish after just one year of attendance in telesecundarias. Estimates show that the existing policy reduces educational inequality, and that expanding telesecundarias would yield significant improvements in academic performance. The third chapter develops and implements a dynamic modeling approach for estimating the effect of grade retention in Portuguese high schools, a setting where over 40% of students were retained. The estimated model is used to simulate academic achievement under existing and alternative retention policies. Results show that the current policy’s average impact on 12th grade math and Portuguese test scores is positive (0.2-0.5 s.d.), but it substantially increases dropout. The chapter concludes by solving for the optimal retention policy to maximize lifetime earnings.