Progress in International Reading Literacy Study (PIRLS) is a large-scale assessment that measures how effective countries are in teaching reading literacy. Conducted every five years since 2001 (with Australia participating since 2011), PIRLS provides information about how to improve teaching and learning so that young students become accomplished and self-sufficient readers. In Australia, almost 5,500 Year 4 students participated in PIRLS 2021. These students completed tests in reading comprehension and answered questionnaires on their background and experiences in learning reading at school. To inform educational policy in the participating countries, alongside the assessment of reading literacy, PIRLS also routinely collects extensive background information that addresses concerns about the quantity, quality and content of instruction. This background information is collected through a series of questionnaires for students, teachers, principals and curriculum specialists.