This study examines developmental associations between leisure reading and reading skills from Grade 1 to 9. As a step further from traditional cross-lagged analysis, we useda random intercept cross-lagged panel model (RI-CLPM) with latent factors to identify within-person associations in a data of 2,525 students on leisure reading (books, magazines, newspapers, and digital reading), reading fluency, and reading comprehension. In Grades 1 to 3 poorer comprehension and fluency predicted less leisure reading. In later grades more frequent leisure reading, particularly of books, predicted better reading comprehension. Negative associations were found between digital reading and reading skills. The findings specify earlier findings of correlations between individuals by showing that reading comprehension improvement, in particular, is predicted by within-individual increases in book reading.