This study examined the role of reading motivation in reading comprehension achievement of 1070 Chilean third, fourth, and fifth-grade students enrolled in public and private schools. Students were assessed in Spanish reading comprehension and were administered the Motivation to Read Profile from Gambrell, Palmer, Codling and Mazzoni (1996), at the beginning and end of the school year. Results showed that motivation to read at the beginning of the school year was significantly associated with gains in reading comprehension skills. When disaggregating motivation into self-concept and value of reading, only self-concept of reading significantly predicted gains in reading comprehension. Moderation analyses showed that students that started the year with lower reading comprehension and higher motivation to read, had significantly better reading comprehension at the end of the school year, than their peers who started with lower reading motivation. The pedagogical implications are discussed.