We review the comparative literature on the impact of national-level educational institutions on inequality in student achievement. We focus on two types of institutions that characterize the educational system of a country: the system of school-type differentiation (between-school tracking) and the level of standardization (e.g., with regard to central examinations and school autonomy). Two types of inequality are examined: inequality in terms of dispersion of student test scores and inequality of opportunity by social background and race/ethnicity. We conclude from this literature, which mostly uses PISA, TIMSS, and/or PIRLS data, that inequalities are magnified by national-level tracking institutions and that standardization decreases inequality. Methodological issues are discussed, and possible avenues for further research are suggested.