Dr. Marks-Tarlow’s paper provides a valuable examination of play processes in psychotherapy, using the novel synthesis of psychoevolutionary and nonlinear dynamical perspectives. The author’s sophisticated blend of psychobiological and intersubjective accounts is of great clinical value, illustrating the need for a rapprochement between affective neuroscience, intersubjectivity, and complexity paradigms. Comparisons are made to the Dynamical Systems Therapy 10 (DST) model (Shapiro, this issue), which similarly aims to integrate psychobiological and intersubjective accounts of psychopathology with internal representations.