The purpose of this article is to highlight commonalities and facilitate links between the domains of psychotherapy and positive psychology. The authors describe the Broaden-and-Build theory and suggest that it has heuristic value for understanding psychotherapeutic processes. The authors propose that broadening represents a common factor in intrapersonal therapy that contributes to many helpful change events across different psychotherapies. The upward spiral in which positive emotions and broadening feed one another enlarges current psychotherapeutic conceptualizations by suggesting that positive emotions are not just indicators but also generators of change. The positive emotion-broadening spiral offers new avenues for research and ways to understand existing research, an alternative avenue to therapeutic change, and a method to tailor therapeutic work to individual clients. It also bridges researcher, clinician, and client points of view about key change events. Links between different viewpoints enhance therapeutic work. Links across lines of theorizing and research foster interdisciplinary ties that fertilize both fields.