This research study intended to discover the perceptions of 10 Illinois Generation Y novice high school principals pertaining to the effectiveness of their principal preparation programs in terms of how well it prepared them to lead in the first three years of their principalship, and what subsequent professional development they deemed necessary for success in the first three years of their principalship. Through a qualitative multi-case study, in which the researcher conducted open-ended interviews, which were triangulated with Arthur Levine's (2005b) Descriptors of Excellence, the Generation Y profile, the student achievement data from each participant's school, the course catalog information from each of the participant's university principal preparation program, and the review of literature, the researcher uncovered themes which described the principals' perceptions of the effectiveness of their principal preparation programs, their perceived impact on student achievement outcomes, and their subsequent professional development needs. Themes emerged in the following areas concerning the participants' principal preparation programs: purpose, curricular coherence, curricular balance, faculty composition, admissions, degrees, research, and assessment. The following themes emerged concerning the participants' perceptions of their perceived impact on student achievement: data based decision-making and articulating student achievement. Finally, the following themes emerged concerning the participants' subsequent professional development needs: collaboration and shared practice, and frequent feedback on effectiveness. It is the hope of the researcher that these conclusions will inform and support the work of educational leadership programs as they are redesigning their principal preparation programs. [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.]