Students' reading losses during the summer are a concern for schools in the United States. The purpose of this investigation was to examine fourth grade students' (N = 5,113) reading development over the summer. The results indicated that students in the lowest two quartiles made achievement gains over summer while these same students evidenced limited reading growth throughout the academic year. In contrast, students in the upper two quartiles evidenced reading losses over summer, although evidencing continuous reading growth throughout the school year. The findings support the need for further investigation of the effects of summer on reading achievement.