One hundred forty six-to-twelve year old children, of both sexes, were individually asked to perform two tasks, based on the doll-placement technique. The first task consisted in arranging a set of 15 dolls on a paper sheet, as they wanted. In the second one Subjects should take two dolls at wish, and suppose there was a given social relationship between them. Subjects should also invent a supposed conversation between the chosen dolls. Data analysis showed the existence of a psychogenetic process of structuration of social knowledge leading to the notion of social relationship, as well as a progressive anticipation of behavioral implications. It was also observed that social thinking becomes increasingly complex with age. Results were discussed in terms of Piaget's theory, and of Berger and Lukmann's propositions on the nature of social reality.