This report aims to increase understanding of educational underachievement among boys and men at the international level. The audience includes researchers, policymakers, and the public. Its purpose is to inform potential policy and program interventions in this area. The report argues that male educational underachievement requires action. The first section of the report takes stock, and examines trends and distributions both between countries and within countries. The second section examines the literature on male educational underachievement, and identifies the principal analytical approaches that have been used to understand and explain the phenomenon. Section three explores the types of interventions that have been adopted by countries to address male educational underachievement. The final section presents the main conclusions of the report and proposes a research agenda. Throughout this report, educational underachievement is referred to in three ways. First, underachievement in terms of low levels of participation in education, including enrollment and retention; second, underachievement in terms of low levels of completion or graduation; and third, underachievement in terms of low student learning outcomes, also referred to as “underperformance”, and assessed in terms of international or regional large-scale student assessments.