In Professional Learning Communities, educators collaborated and focused on ways to improve student learning. Teacher practice was one key component for improving student learning and was the focus of this study. Through the use of a collective case study, the researcher examined how teacher practice was affected through the implementation of Professional Learning Communities. Teacher practice included instructional strategies, classroom curriculum design, classroom management, and assessment and analysis of data. Teacher interviews and observations of both Professional Learning Community meetings as well as classroom instruction were used to collect data. This study focused on understanding how educators used the information discussed within Professional Learning Communities to change teacher practice in order to meet the learning needs of the students. With the small sample size of 3 third grade teachers, a collective case study was the best method to use for this research. Case studies allowed for a small sample size as well as an in-depth, thorough examination of the individuals within the sample. At the conclusion of this study, the findings determined that educator participation in a Professional Learning Community did affect some areas of teacher practice. These areas included classroom curriculum design and assessment and analysis of data. Due to the limitations of this study, the researcher was unable to determine any affect on instructional strategies or classroom management. The affect on student achievement was also not determined in this 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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]