This nonexperimental, cross-sectional, explanatory, quantitative study sought to analyze the influence of length of school day on student performance on the third-grade New Jersey Assessment of Skills and Knowledge Language Arts Literacy and Mathematics total percentage of Proficient and Advanced Proficient scores. The data were obtained from the 2011 New Jersey Department of Education Report Card. The independent variables included school, student, and faculty. The analyses of the data were completed using simultaneous and hierarchical regression models. The results indicated that length of school day had no statistical significance as a predictor of student achievement on the NJ ASK 3. However, the results revealed that socioeconomic status had the strongest statistical significance as a predictor of student achievement, accounting for 28% of the explained variance in Language Arts Literacy and 9% of the explained variance in Mathematics Total Proficient and Advance Proficient scores. [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.]