Student response to instruction is a key piece of information that school psychologists use to make instructional decisions. Curriculum-based measures (CBMs) are the most commonly used and researched family of academic progress-monitoring assessments. There are a variety of reading CBMs that differ in the type and specificity of skills they assess. The purpose of this study was to determine the degree to which the CBM of oral reading (CBM-R) progress-monitoring data differed from nonsense-word fluency (NWF) progress-monitoring data in the presence of a common intervention. We used multivariate multilevel modeling to compare growth trajectories from CBM-R and NWF progress-monitoring data from a geographically diverse sample of 3,000 1st-grade students receiving Tier-2 phonics interventions. We also evaluated differences in sensitivity to improvement and reliability of improvement from each measure. Improvement on CBM-R was statistically, but not practically, significantly greater than NWF. Although CBM-R was not as direct a measure of decoding, it still captured student response to phonics instruction similarly to NWF. NWF demonstrated slightly better sensitivity to growth, but CBM-R yielded more reliable growth estimates. (PsycINFO Database Record (c) 2018 APA, all rights reserved).