The purpose of this quantitative study was to determine if classroom configuration--departmentalized and self-contained--is related to the academic achievement of Grade 6 students in a large urban school district as measured by California Standards Test (CST) scores in mathematics and English Language Arts (ELA) when controlling for prior academic achievement, language, and gender. To this end, existing CST scale scores for the years 2010-2012 were analyzed using hierarchical multiple regressions which allowed the researcher to determine the unique contribution classroom configuration contributed to student achievement. A 22-item researcher-designed questionnaire was also distributed to Grade 6 teachers (n = 36) in the participating school district to capture teacher perceptions regarding what type of classroom configuration is best for Grade 6 students. Three conclusions based on the findings were drawn. First, classroom configuration had no meaningful impact on student achievement in English Language Arts as measured by the CST. Second, classroom configuration had no meaningful impact on student achievement in math as measured by the CST. Third, departmentalized teachers did not differ significantly on opinions of the instructional benefits of each configuration when compared to self-contained teachers. This study presented several implications for practitioners and researchers. One implication is student achievement is due to a variety of factors; therefore, factors outside of classroom configuration must be examined to determine what school level factors best predict student achievement. Quality of instruction most likely makes more of a difference than any structural element. Also, schools should make classroom configuration decisions based on local factors such as student needs and teacher qualifications. Conclusions are inconsistent with some studies aimed at determining the impact of classroom configuration on student achievement indicating further research on the topic is needed. With the current shift in education to Common Core standards and assessments, the study should be repeated in different settings using the same instrument to measure student achievement as this method might provide more consistent findings. Future studies that measure teacher efficacy may also explain more of the variance in student achievement. [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.]