Numerous studies have consistently found negative effects of sibship size on educational outcomes. Three main explanations of these effects have been offered in the literature: (1) the dilution of family resources, (2) a changing intellectual environment in the family for each succeeding sibling, and (3) unobserved selectivity at the family level. In this article, the authors propose a fourth explanation as an extension of the resource-dilution hypothesis: In a traditional or transitional society where resources from all family members are pooled together, families may sacrifice the educational opportunities of older (female) siblings and use their remittance to compensate the family expenses, particularly when there are younger siblings. With analyses of data from the Panel Study of Family Dynamics (PSFD), the authors found empirical evidence to support this explanation. In particular, they found that the negative effects of sibship size are the strongest for girls with younger brothers and sisters who are spaced apart from them. They interpret this unusual high-order interaction involving sibship size, gender, density, and seniority within the context of Taiwan's patriarchal culture, in which families typically favor boys over girls.