This thesis seeks to demonstrate the presence of a social structure based on the organisation of relationships in a group of preschool children. Analyses of interaction frequencies indicate the presence of four distinct friendship groups. Analyses based on semantic classifications of acts (mainly speech) were undertaken and these demonstrated that children do establish mutually meaningful interactions by which differential relationships are expressed. This is achieved through the selective use by the children of inclusive and exclusive behaviours whose distribution was found to conform to the distribution of interaction frequencies. It is argued that these behaviours provide the constitutive bases of the observed social structure by maintaining distinctions in interrelationships. Subsequent analyses of pronominal references indicated that different degrees of mutual involvement are actively sought by children. It is thus demonstrated that children are interested in the formation and maintenance of relationships per se and this leads to the conclusion that psychological research in this area has been constrained by the imposition of excessively restrictive paradigms. The social capacities of the young child have thereby been underestimated. Most research has tended to consider children's relationships within an analytic framework based on individual acts (e.g. Social Learning Theory) or individual cognitions (e.g. Piagetian Theory). This thesis concludes with the assertion that relationships evade explication within a paradigm that only allows for a study of the individual.