The present study examined the impact of an intensive reading fluency intervention on the overall reading performance of 37 struggling readers in 3rd grade. Students' 3rd-grade classroom teachers and/or their performance on a state-mandated reading achievement test given toward the end of the 3rd-grade school year identified them for the study. Selected students participated in a 25-session summer reading clinic. The main instructional intervention was the Fluency Development Lesson, which is an intensive fluency instruction program. Immediately prior to and after the summer reading program clinicians pre- and posttested students on a variety of reading competencies. Analyses of pre- and posttest scores showed that students who had received fluency instruction in the summer clinic made substantial and significant gains in their reading performance. This is noteworthy because despite the fact that many students actually lose ground in their reading achievement over summer, these students made significant reading performance gains. We discuss the practical implications of the results.