Teachers may benefit more from a professional learning community (PLC) than from professional development initiatives presented in single day workshops. The purpose of this program evaluation study was to identify characteristics of an effective PLC and to determine how the members of the PLC have benefitted from the program. Fullan's educational change theory provided the framework for the study, which refers to learning experiences of teachers when collaborating with peers. The sample consisted of 9 biology teachers during the 2012-2013 school year. Data were collected through online surveys and face-to-face interviews regarding effective PLCs. The online survey questions were asked to identify the characteristics of PLCs. Interviews were conducted to examine how biology teachers benefited from PLCs. Survey data were analyzed for descriptive statistics. Interview transcripts were analyzed using thematic analysis for emergent themes. According to study findings, PLCs are used for shared teaching vision and practices. Sustained use of PLCs in schools could help create supportive professional learning environments for teachers to improve their teaching practices through purposeful collaboration. [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.]