Nonlinear dynamics represents an important paradigm shift for understanding complexity, both in the world around us as well as inside of us. Many psychoanalysts interested in the new sciences employ the concepts descriptively. By contrast, Yakov Shapiro has innovated a practical method for applying nonlinear ideas to psychotherapy. In theory his ideas hold great promise; in practice, more work needs to be done.As a fellow psychoanalytically minded theorist and practitioner highly interested in the relevance of nonlinear science to clinical practice (Marks-Tarlow, 2008, 2011, I am pleased to offer commentary on Yakov Shapiro's paper, "Dynamical Systems Therapy (DST): Theory and Practical Applications." In this second of two offerings for Psychoanalytic Dialogues, Shapiro's paper expands his previously laid-out model into a comprehensive dynamical system of psychotherapy.The paper begins with a review of various scientific paradigms as they affect psychoanalysis. Shapiro (this issue) spells out various influences underlying classical psychodynamics. These include thermodynamics, determinism, the classical Darwinian paradigm, the medical model, classical Newtonian physics, and concepts of linear causality. By contrast, Dynamical Systems Therapy (DST) is affected by interactive neural network theory, emergence, neo-Darwinian paradigm, complex adaptive systems paradigm, quantum mechanics, and nonlinear dynamics. Shapiro understands nonlinear science as a metatheory that goes beyond psychoanalysis to underlie all theoretical orientations. Shapiro's model employs an evolutionary foundation, concentrating on complex adaptive systems that self-organize by incorporating both biological and psychological processes. Shapiro aims toward a holistic perspective with conceptual language aimed at lessening the brain/mind divide. Along with linking first-with third-person perspectives, that is, subjective with objective levels, partly by offering the quantum mechanical notion of complementarity.In Shapiro's (this issue) words, A functioning human brain has both subjective and objective aspects to it, in the same way that a photon may behave as a particle or a wave depending on the experimental setup. These aspects of brain/mind reality are inseparable and irreducible to each other; therefore, asking whether a person Correspondence should be addressed to Terry Marks-Tarlow, Ph.D.,