Professional learning communities (PLCs) are a group of educators working collaboratively to improve student achievement and expand the pedagogy of the individual as well as the group. Studies on PLCs, grounded by the social constructivism theory of Vygotsky, Bandura, and Wenger, have found that collaboration and collegiality foster a positive school climate. This case study explored the perspectives of PLC participants at a suburban high school on the impact of their PLC on the school's culture. Ten teacher participants with at least 2 years of experience at the research site were individually interviewed, and 5 observations of content PLC meetings were conducted. Data were open coded to determine emergent trends. The analysis resulted in thick, rich descriptions of the experiences of the teacher participants. The findings suggested that the school's ineffective use of PLCs negatively affected its culture due to a lack of established norms, collaboration, communication, and accountability. A professional learning opportunity was developed focusing on effective PLC usage and the impact on school culture. The study supports positive social change by providing school leaders and PLC participants at the study site with information to sustain PLCs in a manner that promotes a positive school climate that could lead to a more efficient, consistent learning environment that benefits students. [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.]