ABSTRACT
This chapter addresses the question of how intergroup relations are affected by differentiation among subunits, differentiation within them, and the penetration of differentiation into successive subunits. Living in a neighborhood makes a person an inhabitant of a city, a resident of a state, a member of a region, and a citizen of a country. Such concentric circles exist not only in space but also in other dimensions, such as kinship, occupation, and religion. The decomposition of differentiation into that within and that among substructures, however, necessitates a more complex design with two levels of structure and a substantial number of cases within the substructures. The systematic analysis of penetrating differentiation requires some preliminary considerations of basic quantitative properties of variations on several levels. First, the average differentiation on any level is usually greater and cannot be smaller than the average differentiation on any lower level, that is, of the mean differentiation within its subunits.
