This qualitative case study explored assistant principals' practices in instructional leadership. This study was conducted in two small school districts in the South Texas Region 1 area. Research questions included (a) What instructional leadership behaviors are assistant principals in Region 1 engaged in? (b) What support is needed for assistant principals in Region 1 as instructional leaders? (c) What relationship between the principal and assistant principal fosters the instructional leadership practices of the assistant principal in Region 1? The conceptual framework for instructional leadership, based on the Hallinger Model of Instructional Leadership (1985), served as the guide for this study. To triangulate data sources, demographic profiles, interviews, and document analysis were used. The study's findings indicated that assistant principals exhibit a range of instructional leadership behaviors consistent with the conceptual framework of instructional leadership. The data analysis revealed the following three main themes: (a) communication and collaboration skills are vital to the AP role, (b) challenges of being an assistant principal, (c) seeking multiple forms of support. The results of this study add to the body of knowledge on assistant principals by examining the instructional leadership practices used by assistant principals, identifying challenges they face as instructional leaders, and providing recommendations to support the leadership development of assistant principals in the South Texas Region 1 school districts. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]