For my dissertation requirement, I conducted two research projects, collaborating with my dissertation advisor on both projects. In my first project, I employed a phenomenology methodology to investigate how teachers' professional needs, practices, and motivations align with the goals of the professional learning community to enhance teacher efficacy, reflective practice, and collaboration. Our participants were high school teachers entering a long-term grant-supported professional learning community initiative. The teaching experience of our eight participants ranged from one to thirty-nine years in service. We gathered data using semi-structured interviews. We found a diversity of perspectives and practices ranging from traditional approaches to evolving perceptions of the teacher's role in supporting learning. Our results also suggest the brief engagement in the professional learning community initiative influenced the teachers' perceptions of teaching and learning. We failed to find evidence of the professional learning community motivating the teachers to embrace educational innovations or transformations in their teaching perceptions and practices. We conclude our report with a discussion of the findings, implications for the results, and recommendations for future research. In my second study, we conducted a cross-sectional investigation into the influence of professional learning communities (PLCs) on teachers' innovative instruction. We gathered selected response and open-response data from two different populations of teachers, which were grouped by the structure of their professional learning community (PLC). We found that both groups of teachers agreed upon the definition and implementation of innovative instructional strategies. We found the external barriers to innovative instructional strategies included resources and the lack of students' openness to alternative forms of learning. We also found the teacher's need for professional development in innovative teaching, which did not seem to be influenced by their PLC activities. The respondents indicated that the PLCs did influence peer collaboration and learning. Our results indicate that PLCs likely enhanced the participants' awareness of innovative teaching but were not sufficient to lead to implementation. Our findings suggest that barriers remain despite the teachers' involvement in PLCs. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]