At Joseph Case Junior High School, a school located in Swansea, Massachusetts for students in grades six through eight; there was a problematic trend in regard to student achievement in mathematics. Upon completion of an analysis of student cohort results in mathematics on the MCAS (Massachusetts Comprehensive Assessment System), there was an apparent decline in achievement for students when it comes to mathematics in their seventh grade year. More importantly, overall as a school, Joseph Case Junior High School had not met the target for AYP (Adequate Yearly Progress) in mathematics under the performance category since 2006. AYP measures student performance against specific expectations each year. The goals of this quantitative research study were to determine (a) whether single-gender classrooms for males and females in the seventh grade would be a program that would make a positive difference in the declining mathematics achievement seen in the school at this time, (b) to what extent students report being more self-confident learning in a single-gender setting for their mathematics class, (c) to what extent is there a difference between discipline referrals in the single-gender classroom and the co-educational classroom. To support the research questions raised by this proposal, the following literature was reviewed: (1) that which explores the gender gap in mathematics achievement, (2) that which outlines biological differences between males and females, (3) that which examines the single-gender classroom and the influence on mathematics achievement at the middle school level. The underlying question guiding the study is: Will grouping students by gender for math improve their ability to pay closer attention in class and deal with fewer distractions in order to get the most out of the class and show improvement when it comes to MCAS test scores and having an overall better grasp on the concepts at hand? The theoretical framework for this investigation is based on social learning theory and Albert Bandura's explanation of it which emphasizes how observing and modeling other people and their behaviors as well as attitudes and reactions to other is pertinent in the learning process. The impact that socialization has on the learning process, learning styles, and classroom behavior, are important functions of the study. The findings of the study revealed: (a) no difference in academic achievement between the single-gender and mixed-gender classes that were relative to the purpose of the study. (b) students in both single-gender classes reported a higher level of self-concept in their math class, especially the single-gender male class, in comparison to the mixed-gender classes. (c) no difference between discipline referrals in the single-gender classrooms compared to the mixed-gender classrooms. Some implications for further research include the fact that with proper teacher training in single-gender education, and an expansion of the study over a three year period, achievement may be raised. This is partly based on the fact that there was a significant positive difference in the level of self-concept in math class for the students that had a single-gender environment versus those students that had a mixed-gender environment for this particular school year. Keywords: single-gender education, self-concept, social learning theory, developmental theory, math anxiety [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.]