The present study applies the theory of intersubjectivity to language and cognitive development in children, particularly their involvement in joint activities which rely heavily on the intersubjective coordination of mental states (e.g. shared goals, intentions and beliefs about the world) and corresponding actions among participants (Verhagen, 2015; Clark, 1996, 2006). The participation in joint activities has been reported to enhance child development, bootstrapping both their communicative competence and understanding of mental contents of others. To show these effects, we present a qualitative analysis of an interaction between a three- -year-old child and her parent during a social pretend play, investigating both the situations where the child successfully followed the normative rules of a joint activity as well as those where the coordination between the participants was difficult to achieve and the negotiation of participants’ perspectives had to be introduced. Overall, the theoretical perspective based on the intersubjective coordination of participants during interactions not only proved to be fruitful for a complex inspection of child-parent communication, but also, due to its complexity and sociopragmatic basis, demonstrated some advantages over the traditional Theory of Mind model.