Professional learning communities (PLCs) positively influence students' and teachers' success. Yet, traditional professional development, involving passive learning, is still widely used. The problem addressed in this qualitative case study is little is known about administrators' perceptions about PLCs as replacements for traditional forms of professional development (PD). Administrators' and teachers' perceptions of PLCs should be explored to learn more about why PLCs are underutilized in schools, despite their proven effectiveness. The primary conceptual framework used for this study was Knowles' adult learning theory supported by Contextual learning theory. Purposeful sampling was used to recruit eight participants -- four administrators and four teachers - from a school in the Mid-Atlantic United States to participate in this study. Data were collected via semistructured interviews and previous years' PD agendas. Interview data were transcribed and coded manually. A six-phase thematic analysis led to the identification of four emergent themes: (a) Relationships and collaboration create sense of community; (b) Shared local and immediate issues or interests influence buy-in; (c) Ongoing, focused work leads to sustainable change; (d) Cycles of feedback and reflection improve practice; (e) Logistical planning eases tensions; and (f) Shift in mindset is needed for buy-in. Implications for positive social change include the fact that more is understood about the support or resources needed to fully support PLCs, which have been shown to have a positive influence on student achievement. [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.]