The division of labor refers to differences among members of a population in their sustenance activities and the related functional interdependence. It is proposed that the first dimension of the division of labor, sustenance differentiation, may be measured with data on occupational composition. Six alternative measures are presented and evaluated. Emphasis is placed on the attention each gives to the two aspects of sustenance differentiation: structural differentiation (number of classes) and distributive differentiation (distribution of individuals among the classes).