This study uses data on educational expenditure, including specific types of educational expenditure, from the 2009 Socioeconomic Survey of Thailand to investigate gender bias in the allocation of educational resources. Empirical Engel's curves are estimated to test for gender bias. The results show that girls receive more education expenditure than boys. The most likely explanations for this gender bias are: (1) According to the Thai cultural tradition, daughters are expected to be the main caregivers of their elderly parents and (2) wage incomes of daughters are more reliable sources of remittances for parents than the wage incomes of sons.