Education is one of the most important determinants of occupational attainment, and country-comparative scholars have increasingly focused their attention on the stratification of education systems, that is, the extent to which students are differentiated into different groups for instructional purposes. This article introduces a new microlevel risk ignored by previous theories, that is, the risk of productivity loss. I argue that the criterion guiding the first selection into different schools or curricula within a school reduces skill heterogeneity and employers' risk of productivity loss, strengthening the link between education and occupation. Data of the European Social Survey are complemented with new indicators of education systems' characteristics coming from an expert survey that involved more than 200 experts in 34 OECD countries. Findings show that as the first selection is increasingly based on students' ability, the educational gradient in occupational attainment increases for those respondents who achieved an academic upper-secondary degree.