The current study investigated the perspective of principals related to the influence of professional development on their self-efficacy and professional growth. A qualitative, phenomenological study was conducted involving 14 school administrators from 10 different states with vary experience from 2 years to 17 years in an administrative position. The study utilized semi-structured interviews, field notes, and reflexive journals to gather data. Collected data were analyzed through coding and thematic analysis. Principals shared that the top professional development that supports their own professional growth centers around three themes. The themes were collaboration, supports for teachers, and personal investigation. The participants were asked about professional development in terms of building their self-efficacy. The three themes identified were support of staff, collaboration, and mentorship. The findings of this study indicated that the participants rely on relationships with others through collaboration and mentorships to improve both their professional growth and self-efficacy. It is further found that participants desire knowledge to be able to effectively lead as well as spending much of their own time seeking out professional development opportunities. It would be beneficial for opportunities for mentoring programs to be designed to support principals in their current roles. The utilization of individuals who have done the job of principal would be a strong consideration. Districts should consider building in time for principals to collaborate with their peers and work through areas of needed support. Legislatures should consider the creation of specific guidance on the requirement of professional development directly related to leadership. Additional research that would involve principals from other areas of the country would further inform this work. The use of a quantitative correlational study to determine if the quantitative data agrees with the qualitative data previously collected from the initial study, make data-based adjustments to the professional development models currently used for school administrators, and examine the strengths and interactions between factors from the first study. [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.]