The purpose of this two year study was to investigate the implications of a high academic ability learning environment on the achievement scores of third grade gifted students who attended the Florida Brevard County Public School System. Learning environment was defined by the students' academic ability level, whether high academic ability or heterogeneous academic ability, and for this study was the independent variable. Academic achievement, as measured by the 2011 and the 2012 Florida Comprehensive Assessment Test®2.0 (FCAT 2.0) Mathematics and Reading Developmental Scale Scores (DSS), was the dependent variable. Other student data such as gender and socioeconomic status were also collected and used along with classroom structure to examine the extent to which third grade gifted students' reading and mathematics performance could be predicted. Random samples of students were drawn from the third grade gifted student population attending Florida Brevard County Public School System in the 2010-2011 and the 2011-2012 school years. Using an independent samples t-test, analysis of the 2011 FCAT 2.0 Reading and Mathematics found a statistically significant difference in both the students' FCAT 2.0 Mathematics and the students' FCAT 2.0 Reading achievement test scores based on the classroom structure. Specifically, there was enough evidence to support the claim that third grade gifted students who learned in a homogeneous high academic ability learning environment scored significantly higher on reading and mathematics standardize tests than did third grade gifted students who learned in a heterogeneous academic ability learning environment. Approximately 14% of the variance in reading and mathematics scores could be accounted for by classroom structure. However, different results were found with the 2012 FCAT 2.0 Mathematics and Reading scores. The results from the 2011-2012 school year indicated that there was not a significant difference in mean reading and mathematics scores between third grade gifted students who learn in a homogeneous high academic ability learning environment and third grade gifted students who learn in a heterogeneous academic ability learning environment. The recommendations include that subsequent studies incorporate a wider range of grade levels, perhaps even include methods of instructional delivery, types of gifted services provided, and teachers' years of experience. In addition, recommendations are that future studies address the academic performance of high academic ability non-gifted students who learn in homogeneous high academic ability classroom environments verses those who learn in heterogeneous academic ability classroom structures.