We use comparable, survey-based literacy tests for repeated cross-sections of men and women born between 1950 and 2000 to study education outcomes across cohorts in 87 countries. We find that education quality, defined as literacy conditional on completing five years of schooling, stagnated across the developing world over half a century, including absolute declines in both South Asia and sub-Saharan Africa. Shifts in student composition clearly explain part of the downward trend we observe, but the decline pre-dates the abolition of school fees in most countries, and anthropometric data suggest students in later decades were healthier and wealthier than those in earlier cohorts. Globally, increases in schooling outpaced the decline in education quality, leading to a large increase in unconditional literacy