This paper presents the first estimates for a key target of Sustainable Development Goal 4, which requires primary and secondary education that lead to relevant and effective learning outcomes. By developing a new methodology and database, the UIS has produced a global snapshot of the learning situation facing children and adolescents who are in school and out. The data show the critical need to improve the quality of education while expanding access to ensure that no one is left behind. The paper also discusses the importance of benchmarking and the concept of minimum proficiency levels.