This edition of the SDG 4 Data Digest from the UNESCO Institute for Statistics (UIS) aims to help countries develop and report the indicators needed to deliver on the promise of Sustainable Development Goal 4 – a quality education for all by 2030. It stresses the urgency: every child in the generation that should finish secondary education by the deadline should be in a primary classroom right now. Yet, if current trends continue and without a rapid shift from “business as usual”, one in six children aged 6 to 17 will still be out of school in 2030 while just six in ten youth will be completing secondary education. Moreover, there is an urgent need to improve the quality of education on offer. According to UIS estimates, 55% of children and adolescents of primary and lower secondary school age are not achieving minimum proficiency levels in reading and 60% are not acquiring critical skills in mathematics. The investment case for education is clear and has been repeated time and time again: education reduces poverty, improves health and nutrition, advances equity and drives national prosperity. But education systems cannot function effectively without a clear picture of progress – or the lack of it – and without knowing who is missing out on education and why. To help fill such gaps, the Digest focuses on new methodologies to help countries build a full and accurate understanding of their own education successes and challenges while generating the internationally comparable data needed for global monitoring. Through these methodological tools, countries can track and accelerate progress on their own education priorities and contribute to the global achievement of SDG 4.