The subject of organizational effectiveness in nonprofit organizations, although controversial, remains important to both practitioners and researchers. In spite of this, the empirical research on the subject has never been comprehensively reviewed. This article reviews empirical studies of nonprofit effectiveness from the past 20 years. The review reveals that researchers have conceptualized effectiveness in a variety of ways and that the research objectives pursued in the study of effectiveness have changed over time. The review also shows that much recent research has employed an emergent or social constructionist approach to effectiveness that emphasizes issues of process over measurement.