Over the past 20 years, as the study of transparency has evolved into a burgeoning multidisciplinary field, nonprofit scholars have developed an impressive body of research on the antecedents and outcomes of the transparency of nonprofit organizations (NPOs). From both theoretical and practical purposes, it is necessary to develop an overall picture of such antecedents and outcomes, to allow scholars and NPOs to understand why, when, and how transparency should be implemented. Current studies provide a fragmented view, focused on specific elements of NPO transparency; with a systematic literature review of 76 articles, this article offers both an integrative framework of the antecedents and outcomes of NPO transparency and an agenda for research, based on a critical analysis of the integrative framework. Four relevant research orientations emerge: (1) direction of NPO transparency, (2) distinguishing actual from perceived transparency, (3) the dark side of NPO transparency, and (4) NPO transparency contingency factors. Research along these four orientations could add nuance to existing knowledge of transparency and provide key insights with regard to why, when, and how transparency works.