The following article introduces complexity theory as an alternative for conceptualizing the dynamics of change in nonprofit health and human service organizations. We begin by reviewing theories most frequently used to frame change in nonprofits, identifying knowledge gaps that limit their explanatory capacity. The authors then introduce complexity theory as a lens for studying change as ongoing adaptation in dynamic systems; it emerges from the resolution of dualities and can appear unpredictable and nonlinear. Given the criticality of these organizations to public services, we consider new ways of analyzing nonprofit adaptation, and how understanding could lead to enhancing the sector’s capacity to respond to crises.