As much as a bidirectional model of influence has enhanced our understanding of the therapeutic process, this article argues that reliance on two-person models has limited our ability to explore the role that influence plays in therapeutic action. From a psychoanalytic complexity perspective, the manner in which the dyad adapts to influence is a dynamic, emergent property of numerous systems in which the dyad itself is embedded. The conditions that support the dyad's capacity to adapt to and use influence in a manner that builds complexity and supports therapeutic change are explored and contrasted with the qualities of systems that “dread influence” and tend to resist change. From a complexity perspective, therapeutic action involves the dyadic capacity to adapt to one another, as well as to these multiple sources of influence, and to self-organize in a manner that produces and sustains therapeutic change.