This research study, using a mixed method quantitative and qualitative design, investigated the use of professional portfolios as a tool for reflective practice by school principals and vice-principals. The purpose of this study was to examine the impact of the use of professional portfolios on school administrators' personal and professional growth and on teachers and students in their schools. In Phase 1, quantitative data were gathered over a 3-month period through a voluntary online survey completed by school administrators who have a professional portfolio. The survey asked questions about current professional portfolio use, prior experiences with portfolios, as well as enablers, inhibitors, and outcomes of use. Interested administrators were invited through the survey to participate in Phase 2, the qualitative phase of the study, which included 90-minute one-on-one interviews, sharing of professional portfolios and subsequent duplication and analysis, and follow-up e-mail conversations depending on the need. In Phase 2, the connection between portfolio use and reflective practice was explored in greater depth with 12 administrators. Their prior experiences with portfolios and reflective practice, as well as the conditions that supported and hindered portfolio implementation and reflective practice, were investigated. The results provide a description of portfolio use and reflective practice while in the administrator role and reveal that the administrators who participated in this study were enthusiastic about and valued the reflective portfolio process for themselves and for the teachers and students in their schools. Through the process of constructing, organizing, and sharing their portfolios, the administrators in this study reported a positive impact on their professional growth and reflective abilities as well as on their effectiveness as leaders. Many of them became advocates for the portfolio process, openly encouraging teachers, students, and other administrators to use it. Having all stakeholders using portfolios and reflective practice helped to move them towards the development of professional learning communities. The findings also offer suggestions to educators of preservice, in-service, university, and leadership development programs for providing effective professional development about portfolios and reflective practice.