The purpose of this study was to examine the academic achievement of students with disabilities compared to students without disabilities on standardized assessments. This study collected archival data from urban middle schools in six school districts in the State of Georgia. Data was collected from students in grades six through eight on the reading and mathematics sections of the Criterion-Referenced Competency Test (CRCT). The results of the CRCT were analyzed to determine student achievement on the reading and mathematics sections of the CRCT to identify the gap in performance among students with disabilities and students without disabilities. The results of this study indicated that non-disabled students significantly outperformed disabled students in both reading and mathematics across all five years and all three grade levels on the CRCT. The achievement gap in mathematics was larger than the achievement gap in reading. Additionally, the results of this study also indicated that the size of the achievement gap between the two groups of students tended to vary across time. Also, significant decreases in the achievement gaps were found in 6^th and 7^th grade mathematics and 8 ^th grade reading. Conversely, significant increases in the achievement gaps were found in 6^th and 7^th grade reading and 8^th grade mathematics.