The purpose of this descriptive study was to describe Missouri middle-level school principals' perceptions of their instructional leadership practices. The Principal Instructional Management Rating Scale (PIMRS) by Philip Hallinger was used to define the measured leadership tasks (www.philiphallinger.com). There were a total of 77 middle-level principals who participated in the survey. Eighth grade mathematics and communication arts achievement data from the Missouri Assessment Program were gathered from the represented schools for the school years 2008-2010. The survey, demographic, and student achievement data were analyzed through the use of t-tests and multivariate regressions. Cohen's "d" measured effect sizes of the significant differences found. Demographic data included school size, grade configuration, location, socioeconomic status, principal administrative experience, and institutional support. The study found significant relationships within each variable and instructional leadership except for student achievement. Middle school principals rated themselves higher on the survey than did elementary or secondary principals. All principals ranked the job function of Framing School Goals as greatest among the ten job functions subsumed within the three leadership dimensions of the PIMRS. Principals who had help within their building unequivocally scored themselves higher in frequency than the principals who had no formal support from an assistant principal or an instructional coach. Results would indicate that having an assistant principal or an instructional coach significantly influences instructional leadership perceptions. [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.]