The OECD Programme for International Student Assessment (PISA) examines what students know in reading, mathematics and science, and what they can do with what they know. It provides the most comprehensive and rigorous international assessment of student learning outcomes to date. Results from PISA indicate the quality and equity of learning outcomes attained around the world, and allow educators and policy makers to learn from the policies and practices applied in other countries. This is one of six volumes that present the results of the PISA 2018 survey, the seventh round of the triennial assessment. Volume I, "What Students Know and Can Do," provides a detailed examination of student performance in reading, mathematics and science, and describes how performance has changed since previous PISA assessments. [The development of this volume was guided by Andreas Schleicher and Yuri Belfali and managed by Miyako Ikeda. This volume was drafted by Francesco Avvisati with Jeffrey Mo and edited by Marilyn Achiron. For "PISA 2018: Insights and Interpretations," see ED601150.]