This qualitative study described the lived experiences of 17 school administrators. These administrators were 10 principals and 7 assistant principals. The purpose of this qualitative study was to explore public school principals' and assistant principals' viewpoints on the best leadership practices and strategies for leadership advancement of assistant principals. The study was conducted using an Interpretative Phenomenological Analysis (IPA) methodology to examine the lived experiences of school administrators. The population included 17 school administrators, who had at least 2-5 years of school administration in elementary and or secondary education, a master's degree in school administration, and had served or were still serving in a principal or assistant principal role. The participants completed a 45-minute interview that included 10 questions for principals and 12 questions for assistant principals. Qtter.ai and a computerized program were used for the data analysis to identify common themes and patterns. Despite setbacks and challenges, this study explored the lived experiences of school administrators through the lens of Transformational Leadership Model. As a result, this study revealed how important quality mentorship and coaching could provide effective leadership by answering the questions, "What do school administrators perceive as best leadership practices for the career advancement of assistant principals?" and "What do school administrators perceive as professional development strategies for the career advancement of assistant principals?" As our schools have become our main focal point, with more and more educators leaving the profession altogether, this study enlightened the need for support to be in place that do not dim the light of our leaders who want to lead but need adequate training and mentorship on how to lead. [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.]