The search for the principles of unified psychotherapy is an important stage in the advancement of the field. Converging evidence from various streams of clinical science allows the identification of some of the major domains of human functioning, adaptation, and dysfunction. These principles, supported by animal modeling, neuroscience, and developmental psychopathology, along with new theoretical constructs, are demonstrating that human functioning is best conceptualized as holistic and highly interrelated at all domain levels of the total ecological system. Incorporating these findings with evidence accrued over the past century of psychotherapy practice and study allows psychologists to begin to explore the development of a unified system of psychotherapy that is rooted in the clinical sciences. One such attempt to develop a unified framework is presented as a starting point.