Abstract. Human experiences of empathy and presence are quintessential in therapeutic as well as intimate relationships. The work on relational psychophysiology has informed psychotherapeutic research by illustrating how early life physiological concordance between mother and infant are critical in mutual dyadic regulation. These processes cross several developmental domains, including biological, affective, social, and self-identity. By examining physiological concordance, this research has propelled our understanding of mutual regulation into the more expansive understanding of dyadically expanded states of consciousness. The core of the therapeutic relationship inherently engenders expanded opportunities and reorganization of the client, as well as the therapist. By incorporating the views of nonlinear dynamic systems theory, this model views the human as an open dynamic system, consisting of interrelated domains of functioning (i.e., physiological, emotional, cognitive/symbolic, and social/behavioral), where each is an agent in mutual regulation and growth. Fine-tuning the mutual regulation model by bringing in relational psychophysiology and dynamic systems theory offers an expanded understanding of intimate human relationships, including early systemic development between mother and infant, as well as therapist-client effectiveness.