Students of suburban communities have found that social relationships are influenced by the site and. the architectural plans-re-enforcing the proposition that planners can influence social life. But, while physical propinquity does affect some visiting patterns, positive relationships with neighbors and the more intensive forms of social interaction, such as friendship, require homogeneity of background, or of interests, or of values. The planning implications of these findings are developed on the basis of value judgments that positive relationships between neighbors are desirable and that opportunities for the free choice of friends ought to be maximized. These values can be affected by site planning techniques to a limited extent, but they can be implemented only by a moderate-though yet undetermined-degree of homogeneity among the residents. This requirement conflicts, however, with other planning values, for which planners have advocated the balanced community, made up of heterogeneous residents. This problem will be discussed in a second article, to appear in the August 1961 issue of the Journal.