Microtransitions can be identified as those exchanges that occur during everyday life when family members negotiate a change in their interactions. This study aims to highlight how certain aspects of family functioning during microtransitions could influence the development of children's socio-emotional competence in their interactions with peers. In order to achieve this aim, 24 family triads (mother, father, and preschooler child) were observed in a laboratory during semi-structured play activities for a total of 57 interactive sequences; the children were also observed in their nursery school context, where their socio-emotional competence was assessed through the analysis of 142 interactive sequences video-recorded during semi-structured play, and of a questionnaire filled out by teachers. The results indicated that children in families showing a higher degree of coordination were more relationally and socially competent with peers both during the video-observed play and in the descriptions of the teachers.