Scope and Method of Study. The purpose of this study was to evaluate whether the word level composition of curriculum-based measurement reading passages significantly impacted the oral reading fluency performance of at-risk readers. Specifically, the impact of high-frequency and decodable words was evaluated on first-, second-, and third-grade students' absolute reading rate and growth profiles. In the current study, passages containing significantly different levels of high-frequency and decodable words were administered to two groups of students eight times over the course of four weeks. Students read aloud from the passages for one minute and words correct per minute were calculated. Findings and Conclusions. Results from a mixed-model repeated-measures analysis of variance indicated that the percentage of high-frequency and decodable words did not significantly impact either absolute reading rate or reading growth profiles. Visual inspection of grade level data suggested that differences might exist in the reading performance of students who read from the high-frequency and those who read from decodable passages; however, insufficient power prevented statistical analyses of these grade-level differences. Implications for practice and future research are discussed.