In the economic arena, the major manifestation of gender difference has been the extensive specialization and division of labor by sex that has characterized most cultures throughout history. As important and conspicuous as the division of labor between the sexes has been, however, the author argues that economic theory has had little to say on the subject of gender, tending instead to view the customary division of labor as a sociological and/or a biological constant. In this chapter, the author discusses the labor system and traditional masculine and feminine roles.