The following document represents a Problem Based Learning Project (PBL) around the central theme of differentiated instruction leadership. "As demonstrated through literature the emerging problem was elementary school principals lack the necessary understanding and needed preparation in differentiated instruction (DI) leadership to support growth in student achievement." Three central components identified and selected from a breadth of educational research literature are, in no particular order of importance, principals knowledge base about differentiated instruction, principal's perceptions about their preparation in differentiated instruction leadership, and sources of information concerning differentiated instruction leadership. This project has been driven by three guiding questions: 1. What do elementary principals know about effective practices related to leading differentiated instruction programs within their schools? 2. What do elementary school principals report about their preparation to manage differentiated programs? 3. Where do principals acquire their knowledge and skills regarding differentiated instruction program leadership? The team conducted a survey of principals across Missouri to examine their differentiated instruction leadership knowledge base, their perceptions of their level of preparation to lead differentiated instruction initiatives in their school buildings, and where they acquire their knowledge and skills regarding differentiated instruction program leadership. The 24-question mixed methods survey was administered to 557 elementary principals utilizing the membership database of the Missouri Association of Elementary School Principals. Principals surveyed represented a variety of socioeconomic populations, geographic areas, and student enrollments. One hundred and thirty principals completed the survey. The team found Missouri principals had high confidence in their knowledge of how to lead differentiated instruction initiatives in their school buildings and their preparation to lead those initiatives. Finally, the research team found the primary sources of knowledge and preparation to lead differentiated instruction initiatives were not formal principal preparation programs or the Missouri Department of Elementary and Secondary Education, but sources outside of the formal setting, such as on the job classroom teaching, another teacher or administrator, or professional reading. As a result, the team provided recommendations for administrator preparation to lead differentiated instruction initiatives for principal preparation programs and principals who have completed a formal principal preparation program. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]