AbstractThis study is concerned with assessing whether social marking, i.e. the correspondence between the cognitive solution of a task and the social relation expressed in the material, is a mechanism of cognitive progress which depends on specific forms of socio‐cognitive conflict or on presence of familiar social relations in the material. In the first experiment 5‐6‐year‐old non‐conserver children were selected during a pre‐test that comprised three spatial transformation tasks. During the test phase, 56 children worked on spatial transformation tasks with an adult partner in four socially marked conditions in which the correctness of the adult model varied. All subjects were individually post‐tested on the same tasks with unmarked content. Results showed that, under the same marked conditions in the test phase, more progress took place, at the post‐test phase, when subjects had interacted with an incorrect adult model than when they had interacted with a correct one. In the second experiment the hypothesis of an interaction between the nature of the material and the kind of social interaction was examined by means of a factorial design in which the factors were adult versus child partner and marked versus unmarked material. The procedures in the pre‐ and post‐test phase were carried out in the same way as in Experiment I. In the test phase 61 non‐conserver children interacted with partners who presented completely incorrect model. The results of post‐test phase indicated that there was a main effect of social marking although findings of a condition in which children interact with another child on unmarked material also have shown a certain amount of progress. The findings are discussed with respect to the psycho‐social model of cognitive development.