Despite significant investments, lower-income countries face a learning crisis. A clamor has thus arisen worldwide for greater accountability of those involved in service delivery. To obtain new insights, the UNESCO Global Education Monitoring Report was dedicated to accountability in 2017, and the research on this topic was reviewed. A summary is published herein. Accountability seems strongest in explicit hierarchies with direct principal-agent relations, as in an army, and when individual contributions are identified. It is enhanced when tasks are clearly defined, information is sufficient, and sanctions for violators are significant and credible. People may demonstrate better judgment if they are accountable for procedures, such as teachers using class time efficiently. By contrast, accountability for difficult outcomes, such as students' actual memory consolidation, results in avoidance and efforts to limit one's role. Conditions inherent in the education sector may compromise accountability. Government officials, who frequently change, are accountable to groups, whose staff and consultants also change. At the school level, parents rarely have principal-agent relations with staff, so the latter may feel little obligation to teach. In complex organizational settings, accountability could be enhanced by identifying individual contributions to a task, providing comparison standards, imposing significant and enforceable sanctions, and focusing on processes and decisions rather than strictly on outcomes. The Sustainable Development Goals will be more easily fulfilled if governments and donors can mitigate the effects of this little-understood phenomenon.