While new modes of data processing have provided reams of data, there has been relatively less effort in seeking to comprehend the social meaning of results of empirical work. A set of previously developed indicators of urban social structure is here examined for its link to theory, and to the social structure of the city itself. The original indicators (size, social class, racial composition and community maturity) were empirically derived. In this paper, each is taken in turn, and explored with respect to several possible social meanings. Size, for example, is considered to be itself an indicator, and an imperfect one, for system complexity; percent non-white is seen to be itself an indicator for a slowdown in the mobility process, or a slower social metabolism. These and other results are suggestions, with illustrations, but not conclusive support, from other than the original data. While it is hoped that the theoretical suggestions may themselves be of interest, it is also hoped that approach itself can indicate the fertility and usefulness of going back to theory once empirical measures have been developed.