The implementation of new inclusion practices has introduced a new conceptual framework for finding strategies to aid low-ability students in achieving increased academic success. Grouping within heterogeneous-ability classrooms has become the mainstay for educational reform, yet limited empirical evidence exists to document to what extent the approach is generalizable and effective across diverse local applications. The aims of this quasi-experimental study were to examine the differential effect that heterogeneous grouping and homogeneous grouping have on low-ability, eighth grade students in the science content area. The research questions for the study considered whether there was a significant difference in the academic achievement eighth-grade science students of low-ability placed in heterogeneous-ability versus homogeneousability groups, and whether there was a significant difference in the academic achievement across all eighth-grade science students placed in heterogeneous-ability versus homogeneous-ability groups. Independent sample t-tests were used to examine differential achievement gains across heterogeneous/homogeneous group conditions. These analyses confirmed the there were significantly greater science score gains for low-ability students placed in heterogeneous-ability than for low-ability students placed in the homogeneous-ability groups. No significant differences in science score gains were observed when comparing all students placed in heterogeneous-ability to all students placed in the homogeneous-ability groups. Implications for social change include providing empirical evidence to inform decision making and guide best practices toward accelerating academic achievement for lower-ability students.