An increasing number of schools are implementing gifted cluster grouping models as a cost-effective way to provide gifted services. This study is an example of comparative action research in the form of a quantitative case study that focused on mathematic achievement for nongifted students in a district that incorporated a schoolwide cluster grouping model. Although previous research found that gifted students performed better in the cluster setting, this study sought to determine the effects of the cluster model on nongifted students. Findings from this research indicate that general education students in the gifted cluster classes and those not in the gifted clusters experienced similar levels of academic growth in mathematics. Data disaggregated according to grade level, gender, ethnicity, and English language learner status showed that students achieved at similar rates in mathematics in gifted cluster classrooms and those classrooms without the gifted cluster groups. (Contains 7 tables and 1 note.)