This study sought to investigate the relationship between middle school principals' instructional leadership behaviors and student achievement. In particular, this study investigated the specific principal leadership behaviors of middle level principals that promote student achievement in school. A secondary variable for consideration was student socioeconomic status (SES). This was a quantitative data analysis study that examined the relationships between principal instructional leadership behaviors as perceived by principals and teachers as measured by the Maryland School Assessment (MSA). This study also investigated the extent that the interaction of principal instructional leadership behavior scores as perceived by principals, and student socioeconomic status (SES) explained the variance in student performance in grade eight mathematics and reading as measured by MSA. Additionally, this study examined the extent to which teacher--perceived principal instructional leadership behavior scores explained the variance in math and reading scores in grade eight, as measured by the MSA. Statistical analyses such as Person-Product Moment Correlations, and standard regression to describe the relationships that occur among variables that influence student achievement were conducted. The results of these analyses revealed findings related to principal leadership behaviors and 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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]