The purpose of this mixed study was to investigate the differences between higher and lower achievement middle school rates pertaining to leadership qualities, opportunity to learn, instructional practices, parental involvement, and professional development. Qualitatively, principals were interviewed using a semi-structured interview protocol. Quantitatively, the teachers in this study were surveyed to investigate the difference between higher and lower achievement rate and teacher responses regarding the variables. In addition, this study investigated the variables and demographics that predict student achievement. The independent variables were opportunity to learn, instructional practices, parental involvement, leadership qualities, and professional development. The dependent variable was student achievement, which was measured using New York State (NYS) English Language Arts (ELA) and Math 8 Grade scores. A significant finding in this study was that the student demographics did not have an impact on student achievement. English language learners were exactly matched between each pair of higher and lower performing schools. Students with disabilities and race were also closely matched. Additionally, this study finds economic disparity to not be an indicator for student achievement. Furthermore, this study found that OTL was utilized in higher performing schools more than in lower performing schools regardless of SES according to the teachers surveyed. [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.]