This study examined the association between infant developmental milestones and educational level at 31 years of age in the Northern Finland 1966 Birth Cohort (n=12 058). Developmental data (age at standing, walking, speaking, and measures of bowel and bladder control) were gathered from children's welfare centres. Information on type of schooling at 14 years of age was reported by children and parents. School achievement at 16 years of age and educational level at 31 years were obtained from national registers. Those who reached infant developmental milestones sooner in their first year of life had significantly better (p<0.05) mean scores in teacher ratings at 16 years, and at 31 years they were more likely to have achieved a better educational level than slower developers. The adjusted odds ratios for individuals who developed more slowly to remain at a basic educational level (7 to 16y) ranged significantly from 1.1 to 1.3. The possibility of advancing from secondary to tertiary level was 1.4 times greater in faster developers than in slow developers. In conclusion, those who develop faster during their first year of life tend to attain higher levels of education in adolescence and adulthood.