This study examines the relationship between family size and children’s education in Bangladesh for two periods – 1982 with high fertility and 1996 with low fertility – using data from the Matlab Health and Demographic Surveillance System of the ICDDR,B: Centre for Health and Population Research. Children aged 8–17 years (27,448 in 1982 and 32,635 in 1996) were selected from households where the mother was aged 30–49 years and the father was the head of household. Children’s education was measured in terms of completed years of schooling: at least class 1 (among 8–17 year olds), at least class 5 (among 12–17 year olds) and at least class 7 (among 15–17 year olds). After controlling for all variables in the multivariate analyses, level of children’s education was not found to be associated with family size during the high fertility period. The family size–education relationship became negative during the low fertility period. In both periods children of educated mothers from wealthier households and those who lived close to primary/high schools had more education, but this socioeconomic difference reduced substantially over time. Boys had more education than girls during the high fertility period but this difference disappeared during the low fertility period. As birth rates fall and the proportion of children from small families increases an increase in children’s education is to be expected.