Rapidly growing costs of elementary and secondary education are studied in the context of the rising value of women's time. The dramatic increase in direct costs of education per student in the past 3 decades is empirically linked to increasing demand and utilization of teacher and staff inputs, attributable to growing market opportunities for women and changes in the structure of families. On the supply side, the "flexibility option" that female teachers who take temporary leaves do not suffer subsequent wage loss upon reentry, is shown to be an important attraction of the teaching profession to women.