Three multivariate analyses, all controlling for the effects of poverty, confirm the importance of the library. Replicating McQuillan's analysis of 1992 NAEP scores, this study finds that access to books in school and public libraries was a significant predictor of 2007 fourth grade NAEP reading scores, as well as the difference between grade 4 and grade 8 2007 NAEP reading scores, suggesting that access is important for improvement after grade 4. Access (school/classroom libraries) was a significant predictor of scores on the PIRLS test, a reading test given to fourth graders in 40 countries. (Contains 13 tables.)