Summer loss of reading is a potential factor in maintaining, and potentially widening, the achievement gap. This study used curriculum-based measurement of reading (R-CBM) to investigate the effect of the summer on reading. For this study, 317 students in Grades 2 to 5 were assessed in the spring and fall using Dynamic Indicators of Basic Early Literacy Skills Oral Reading Fluency (ORF) measure. Repeated measures analysis of variance modeled overall change in ORF scores by grade, family income, ethnic minority status, English language learner status, and special education (SPED) status. Students in Grades 2 and 3 evidenced overall summer loss, whereas students in Grades 4 and 5 did not exhibit summer loss. In addition, students in Grade 2 showed differential loss based on family income and SPED status. These results support the broadening application of R-CBM and add to the summer loss literature. Findings are discussed relative to prevention and intervention. (Contains 3 tables.)