Much of the considerable confusion about the definition of social entrepreneurship in academic literature stems from a lack of empirical research on the subject. This article advances social entrepreneurship research beyond conceptualization discussions by developing and validating an instrument that quantifies the incidence of nonprofit entrepreneurial behavior. Information from 145 Kansas City Metropolitan Area nonprofit organizations was collected to validate the underlying constructs represented in the instrument. Behavior differences were depicted between entrepreneurial and nonentrepreneurial nonprofits. Using principal component factor analysis, the research illustrates social entrepreneurship as a unique nonprofit behavior that occurs at the intersection of innovation, proactiveness, and risk taking.