The purpose of this quantitative nonexperimental causal comparative research study is to determine if there is a statistically significant difference in reading and math achievement as measured by the Georgia Criterion-Referenced Competency Test (CRCT) for sixth, seventh, and eighth grade students with disabilities (SWD) who attended the afterschool program of one rural Georgia middle school when compared to sixth, seventh, and eighth grade SWD who did not attend the program. The results of this research are important because they will identify practices used in the specified afterschool program to improve the academic achievement of SWD. A quantitative research method using a causal comparative design was used to assess the impact of the afterschool program on the student achievement of SWD as an intervention to improve student achievement. Using analysis of covariance (ANCOVA), the study compared two groups of SWD from each grade level: one group attending the afterschool program and the other group not attending the program. Georgia CRCT reading and math scores of those who participated were compared to students who did not participate in the afterschool program. Results showed that there was no statistically significant difference between the groups of SWD for all grade levels and both reading and math. Conclusions and recommendations for further research are included. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]