This study explores the relationship between practice at reading, student reading performance, and organizational features of the school system. Data generated through a program for computer-assisted student self-assessment of reading comprehension (The Accelerated Reader) were gathered as a measure of reading practice for over 659,000 students in grades K-12 in one school year. Students and states performing high and low on reading tests were compared. The data suggested that student reading ability was strongly positively related to amount of in-school reading practice. The time allocated in school to reading practice on self-selected materials declined after grades 5/6. The amount of reading practice was negatively correlated with school size. More reading practice occurred in private than in public schools. Implications for action are discussed.