The study explored the different kinds of instructional structures used in elementary schools in Virginia and why they were used according to principals. The findings and implications of this study are important to the field of school leadership and instructional structures. No study in the past has provided a rich description of how and why instructional structures are used. The analysis of the principal interviews, for instance, reveals that in regard to teacher-allocation structures, principals only use the terms departmentalized, two-teacher teams, and self-contained. This finding directly contrasts with most of the literature, which uses many different terms to describe instructional structures in elementary schools. The use of instructional structures in elementary schools is, for the most part, complex and varied. Dozens of past studies have lumped the different structures together under a few headings. This study suggests that every school's use of instructional structures is a little or a lot different from that of another school. Whether or not these differences help explain differences in teaching effectiveness and student outcomes remains to be determined. In this study, principals gave sound reasons for the use of instructional structures in their schools--reasons that were based in the literature, or in a few cases, should be added to the literature. Elementary schools, like any organization, are complex entities, and research in this area should take that complexity into account. [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.]