This study determined whether chronological age differences among students in the same grade level affected their respective levels of academic performance on the Pennsylvania System of School Assessment (PSSA) mathematics assessment. The study analyzed the additional independent variables of gender, socioeconomic status, and special education (identified as having an Individualized Educational Plan [IEP] other than gifted) to determine if they contributed to differences in student performance. The study sample consisted of 16,043 students from grades 3, 5, 8, and 11 in 40 randomly selected Pennsylvania school districts. This quantitative design analyzed the data using an analysis of variance (ANOVA) and a post-hoc Tukey HSD to determine whether there was a significant difference between student performance on standardized PSSA mathematics assessments and chronological age. The study also employed an ANOVA to identify interactions between the additional independent variables, gender, economic status, and IEP, within each grade level and student performance on standardized PSSA mathematics assessments. A multiple regression analysis determined whether the independent variables within each grade could predict student performance on the PSSA mathematics assessment. This study found significant differences in mathematics performance between chronological age groups. Further, the data showed significant differences between the independent variables and student scores on the PSSA mathematics assessment. [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.]