Results of a survey of semi-matched samples in two rural sites in Thailand indicate that family size has an important impact on children's education. The number of children in a family and the likelihood that a child will study beyond the compulsory level are inversely associated, even when other important determinants of children's schooling are controlled. Survey results and qualitative data collected through focus groups also reveal that in Thailand the primary responsibility for funding children's education falls directly on parents. Thus more children readily translate into reduced resources available per child and hence less education. Given the inverse association between family size and children's education, the fertility decline that is under way is likely to contribute to rising levels of education by changing the distribution of children with respect to family size.