Although sibship size has become a standard measure in the study of academic achievement and attainment, logical and theoretically meaningful extensions of this variable often have been ignored. Sex composition--the number of brothers and the number of sisters--is one such extension. This article reports on a study of the impact of sex composition on strategies for funding a college education. Data on 454 seniors at two large universities confirm that the number of brothers poses a greater obstacle than does the number of sisters to parents' financial support of their children's college education. In addition, the alternative means by which students fund their college education are more strongly affected by the number of brothers than by the number of sisters they have. The authors conclude that sex composition of sibship strongly merits inclusion in educational research.