The paper develops a theory of partial similarity and outlines on that basis a new conceptual framework for the analysis of social distance and coordination. In particular, it is argued that the individual filtering of information may be significantly different from one subject (or social group) to another, so that the likelihood of social congruence is enhanced by individuals’ ability to spot features of partial similarity across a variety of contexts. (A social context is informally described as the set of conditions under which any specific co-ordination pattern, or set of coordination patterns, is feasible.) A remarkable consequence of this shift of emphasis to co-ordination contexts is that, in a social universe characterized by a sufficient degree of internal differentiation, limited rationality makes congruence more likely. A necessary condition for that is that individuals should be skilled social actors, so as to be able to identify similar attributes across a large number of individual (or social) types. This suggests that social equilibrium may be the unintended outcome of multiple cases of ‘niche co-ordination’. In this case, however, the different niches should belong to a social continuum in which individuals (or groups) share certain features with adjacent individuals (or groups) though by no means with all agents in the same social set. Social congruence may be differently construed depending upon the rationality framework in which interaction takes place. A cognitive setting characterized by the ability to detect unusual connections in a diverse social universe is one in which rationality is local and practical rather than ‘universal’. In this case, multiple foci breed distinct perspectives from which co-ordination may be sought. Circumscribed rationalitys suggests inferential diversity. The latter expresses itself by means of manifold attitudes to similarity and conceptual association. Indirect social knowledge may be derived from direct experiences as a result of lateral exploration (exploration within a continuum of partial similarities). And this process normally follows a different route depending upon the specific context in which each individual elaborates her (his) own cognitive endowment. This approach makes congruence an unintended outcome of social diversity, provided the latter follows the pattern of partial similarity and limited (local) difference described above.