Non-governmental organizations (NGOs) are pivotal actors in international affairs. They manage billions of dollars in funding, work all around the world, and shape global policies and standards. It thus comes as no surprise that the subject of accountability has drawn the interest of an increasing number of scholars across disciplines. Though there seems to be agreement about its desirability, accountability is also described as chameleon-like and ambiguous. And despite calls for more cross-disciplinary learning and conceptual clarity, there does not exist a comprehensive review of accountability conceptualizations across and within disciplines, or how the different meanings relate to each other. Based on the conceptual review of 217 research articles published within the last twenty years, this study identifies and analyzes conceptualizations of accountability in the major journals of five engaged disciplines: accounting, development studies, international relations and political science, organization studies and management, and public administration. Integrating this broad scholarship reveals that: (1) there exist 113 different conceptualizations of accountability, 90 of which are rarely used and appear in less than 5 percent of all analyzed articles, (2) scholars have used forty-three different conceptualizations in 2019 compared to seventeen conceptualizations in 2009, (3) many conceptualizations refer to same phenomena by different name (duplication), and different phenomena by the same name (conflict), and that (4) conceptual ambiguity contributes to ambiguity among the forty different terms used to measure and operationalize accountability. These findings illustrate a lack of cross-disciplinary learning and accumulation of knowledge, and suggest that new conceptualizations be introduced only if one or more of the 113 existing ones don't already capture an idea sufficiently. The purpose of this article is to serve as a concept map for scholars when debating and charting new directions for the study of accountability.