Education can generate important externalities that contribute towards economic growth and convergence. In this paper, we study such externalities and their drivers by conducting the first meta-analysis of the social returns to education literature. We analyse over 1,000 estimates from 32 journal articles published since 1993, covering 15 countries of different levels of development. Our results indicate that: 1) there is publication bias (but not citation bias) in the literature; 2) spillovers slow down with economic development; 3) tertiary schooling and schooling dispersion increase spillovers; and 4) spillovers are smaller under fixed-effects and IV estimators but larger when measured at the firm level.