Research shows a math achievement gap for at-risk and economically-disadvantaged students in the United States. To address this issue, a Texas school district implemented a 90-minute math block-scheduling program with 8th grade students. Shaped by the academic learning time and social justice theories, the purpose of this quantitative program evaluation was to determine if students in 3 key subgroups (low performing, low performing and at-risk, and low performing and economically-disadvantaged) who participated on the 90-minute block-schedule performed significantly better on the math state standardized assessment than did students in the same subgroups who remained on the traditional schedule. This retrospective causal-comparative design compared existing scores from the 2013 Math State of Texas Assessments of Academic Readiness (STAAR) of 109 8th grade students (n = 49 block-schedule; n = 60 traditional schedule) for each of the 3 key subgroups. Mann-Whitney U tests indicated no significant differences in Math STAAR scores for the 90-minute block-schedule groups versus the traditional schedule groups for any of the 3 key subgroups studied. Results suggest the 90-minute block-scheduling program was not effective in producing better math assessment scores compared to the traditional schedule for these students. Findings were presented to district decision makers in an evaluation report, which may motivate district stakeholders to reevaluate current educational practices and funding allocations to improve math achievement of low performing students and produce positive social change. [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.]