Evidence is presented on investments in years of schooling in men and women across countries and within countries over time. The ratio of enrollment years or public educational expenditures on women relative to men is increasing toward unity for industrially advanced countries in the second half of the Twentieth Century, and is approaching this balance in Latin America and South East and East Asia. But in South and West Asia and Africa young women receive about half the amount of public expenditures on education as do men. This paper examines evidence on wage differentials by educational attainment for men and women to assess whether the lower levels of investment in schooling of women than men in many low income countries is explained by a lower private or social return to schooling among women. To calculate these returns to schooling, analysis relies on potentially unrepresentative subsariiples of wage earners. A sample selection statistical correction methodology is proposed and implefnented to deal with this problem. It assumes that an individual's ownership of land, assets, and nonearned income raises the opportunity value of the individual's time in nonwage activities, and thereby reduces the likelihood of being in the sample of wage earners, without influencing market wage offers. Estimates from Thailand, Cote de'lvoire, Ghana and elsewhere, as well as for the United States, are compared to assess how corrected returns to schooling are related to the wide variation in school investments between women and men across contemporary low income countries.