This paper assesses inequality of opportunity in educational achievement using the Human Opportunity Index methodology on data from the Programme for International Student Assessment. The findings suggest that there are large inequalities in learning outcomes as measured by demonstrated proficiency in Programme for International Student Assessment test scores in math, reading, and science. Differences in wealth, parental education, and area of residence explain a bulk of this inequality in most of the countries in the sample. Consistent with what has been documented previously in the literature, the paper also finds a strong and stable correlation between inequality of opportunity and public spending on school education. An exploration of the changes in inequality of opportunity between the 2009 and 2012 rounds of the Programme for International Student Assessment, using parametric and nonparametric techniques, suggests that there has been little progress.