PIRLS (Progress in International Reading Literacy Study) was inaugurated in 2001 as a follow-up to International Association for the Evaluation of Educational Achievement's 1991 Reading Literacy Study. Conducted every five years, PIRLS assesses the reading achievement of young students in their fourth year of schooling--an important transition point in their development as readers. Typically, by this time in their schooling, students have learned how to read and are now reading to learn. Fifty countries from around the world participated in the PIRLS 2016 international assessment of reading comprehension at the fourth grade, and in every country there was a wide range of reading achievement from basic skills to advanced comprehension. The "PIRLS 2016 International Results in Reading" includes 10 chapters or sections providing overviews in the form of infographics and numerous exhibits summarizing student achievement distributions, performance at the PIRLS International Benchmarks, achievement trends over time, and achievement in relation to students' home, school, and classroom educational contexts for learning to read.