The purpose of this study was to investigate the relationship between music instruction and mathematics achievement scores for 6th grade students at an Atlanta public school. Guided by Gardner's multiple intelligences model, neurological research, and National Consortium of Arts Education research, this study used a quasi-experimental causal-comparative research design method. Data were collected from 81 6th grade students who did not receive music instruction and 28 6th grade students who received music instruction through band, chorus, or orchestra. A power analysis was used to calculate the minimum sample size required to be reasonably likely to detect an effect of a given size. The standardized test data were from the Criterion Referenced Competency Test Criterion Referenced Competency Test. An analysis of covariance (ANCOVA) was used to determine music instruction scores on the CRCT mathematics tests. The students' scores from the 5th grade (2008) school year served as the pretest data, and the scores from the 6th grade (2009) year served as the posttest data. A 1-tailed significance level of 0.05 was used to evaluate the results for each research question. Results showed a statistically significant difference in scores between the two groups. Students who received music instruction during the year scored an average of 12 points higher than students who did not receive music instruction. The results of this study indicated public school districts might be able to increase standardized mathematics test scores by mandating all students in Grades K-8 to be enrolled in a quality music course every year. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]