This study explored the effect of public library activities on reading achievement of 1stgrade students, using the ECLS-K (Early Childhood Longitudinal Study-Kindergarten). The results from Analysis of Covariance (ANCOVA) indicate that children's reading Item Response Theory (IRT) scores were significantly related to whether their parents had a library card and visited the public library with them. In addition, the reading IRT scores of 1stgrade students who had their own library cards were significantly higher than those of non-library card holding students. The location of the public library also played an important role in the number of times parents and their children visited it. Students who visited the public library also had significantly higher reading IRT score than students who did not visit the public library. These findings suggest that accessibility and utilization of public libraries contribute to the growth of reading abilities of 1stgrade students. © 2012 Authors.