The Progress in International Reading Literacy Study (PIRLS) provides an objective assessment of the reading comprehension attainment of Grade Four primary school students in countries worldwide. Organized by The International Association for the Evaluation of Educational AchievementInternational Association for the Evaluation of Educational Achievement (IEA), PIRLS assesses primary school students’ reading attainment, reading behaviour and attitudes towards literacy in some 50 countries and within-state regions globally. The Centre for The Advancement of Chinese Language Education and ResearchThe Centre for The Advancement of Chinese Language Education and Research of the University of Hong Kong (CACLER, HKU) was commissioned by the Education Bureau of the Government of Hong Kong SAR to participate in implementing the PIRLS research in Hong Kong. The PIRLS 2021 survey presents objective evidence of Hong Kong primary school students’ reading ability and how this compares against that of students of the same age around the world. It also enables educationists, schools and the general public to monitor the reading ability of Hong Kong primary school students over the years and to evaluate the impact of factors that have influenced performance. The Hong Kong element of the PIRLS 2021 data collection was conducted from April to June 2021. Students, their parents or guardians, Chinese Language teachers and school principals of the participating schools completed questionnaires that supplied information about the school the child attended, the reading syllabus and school curriculum, students and staff. The study sought to examine how students’ attitudes towards reading, their home environment, school environment and pedagogy encountered in the classroom had influenced students’ reading proficiency.