The success of a Professional Development School (PDS) is dependent upon the PDS principal and her/his ability to negotiate diverse job responsibilities, the most important being an effective instructional leader. Therefore, the issue that was addressed in this study was: What are the exemplary practices of PDS principals in the area of instructional leadership? Mixed methods methodology was used for this study. Ballinger and Murphy's (1995) Principal Instructional Management Rate Scale (PIMRS) was used to gather quantitative data from PDS principals that responded to an email invitation to participate in the study. Qualitative data was gathered through interviews with PDS principals. Participants came from 20 PDS elementary schools, 3 PDS middle schools and 2 PDS high schools in 14 states. The Wallace Foundation's (Perspective, 2012) five elements of proven instructional leadership practices were used as a theoretical framework. These were compared and contrasted with the findings of the PIMRS (Hallinger & Murphy, 1985) survey results and principal interviews. The study identified eight exemplary practices of PDS principals in the area of instructional leadership. The practices that emerged from the study were: strong visionary teams, open communications, developing of relationships, support needs, the importance of an administrator being available and involved, strong planning and organizational skills, acceptance, and flexibility. Seven constraints to PDS principals in their instructional leadership practice were revealed. The findings demonstrate the need to place instructional leadership at the forefront of PDS principal training and professional development and have ramifications for policy reform and future administrative leadership and educational change studies. [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.]