Since psychotherapy is an activity aimed at change, here we consider it as an example of interpersonal creative process. In this context, creativity consists in identifying new and adaptive solutions to common problems, a skill that can be learned and exercised within a “proximal development zone”. Secondly, it is proposed that the evolutionary social mentality of play is the elective context for the development and the exercise of creativity. Finally, we argue that therapeutic change is the result of a recursive interpersonal process of security seeking and joint advance towards novelty, characterized by an alternation of comfort and enjoyment that leads to increasing levels of intersubjectivity. Play informs and nurtures the thriving instances of this process; therefore, it is proposed that the social play is the engine of creative processes of change in psychotherapy. Finally, some critical issues are discussed which have probably hindered a more playful conception of therapy, and some possible lines of development are sketched for a future operational definition of playfulness as a clinical method.