This paper explores the relationship between public libraries and school achievement. Medellin counts on a system of public libraries. However, public library parks are part of a separate system. The library parks are understood as cultural centers for social development that seek to encourage the meeting of citizens and to develop educational activities that involve the digital culture. The project began in 2004 and was consolidated until 2011 with the introduction of 9 different library parks. Using an approach of differences-in-differences and matching techniques, we explore the effect of the library parks in Medellin on school performance. We found a significant effect on the performance of the language test in the students treated, especially in the long-term specification. Key Words: Public libraries, school achievement, impact evaluation, public investment. JEL Classification: C33, H54, H76, I2, I26.