Purpose: The purpose of this dissertation was to determine the extent to which school instructional calendar configuration (i.e., year-round or traditional) influenced Grade 5 student academic performance as reflected on the Texas Assessment of Knowledge and Skills (TAKS) test as a function of student ethnicity (i.e., Hispanic, White, and Black) and programmatic enrollment (i.e., economically disadvantaged, Limited English Proficient [LEP], and special education). These variables were examined across three Grade 5 subject tests (i.e., English, mathematics, and science). Finally, analysis was conducted for the 2004-2005 through the 2010-2011 school years. Methodology: A causal-comparative research design was utilized in this research. The TAKS Reading, Mathematics, and Science scale scores were acquired from the Public Education Information Management System (PEIMS) database. Schools designated as YRE campuses were selected from the NAYRE 2010 listing of Texas YRE school campuses. Schools included in the traditional public school group were selected using campus comparison data obtained from AEIS comparable improvement reports. For each year-round school used in the study, two demographically similar traditional calendar schools were chosen for comparison based on similarities in the percentage of Black, Hispanic, White, and LEP students enrolled at each campus. All Grade 5 students who attended and took the regular English Language version of the TAKS test on these campuses were included in the study. Grade 5 students who attended charter schools and separate alternative campuses were not considered for analysis. A MANOVA technique was used to analyze the data. If a statistically significant result was revealed, then univariate follow-up ANOVA procedures were performed. Results: Grade 5 Hispanic students and students who were economically disadvantaged overall appeared to have benefitted from attending YRE schools as evidenced by higher TAKS Reading, Mathematics, and Science scale scores, whereas White and Black students appeared to have not statistically significantly benefitted from attending YRE schools. Students designated as LEP appeared to have benefitted more from attending traditional calendar schools versus YRE schools based on TAKS scale scores. Statistical analyses of the differences in TAKS mean scale scores for students enrolled in special education at traditional calendar and YRE schools yielded mixed results. [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.]