The DuFour PLC model is one of several reforms today based on the theory that organizing teachers into learning communities will promote professional collaboration and collegial relationships which will improve teacher skills, motivation, and increase student achievement. A small number of studies have explored the impact of PLC's on teaching practice and student learning, however, none of these studies have explored PLC's in a music ensemble environment. The primary purposes of this study are to determine the impact of PLC's on teachers' sense of community and professional skill, and to determine the impact of PLC's on student achievement in a middle school orchestra setting within a six-week time period. To achieve this purpose, the researcher analyzed teacher attitudes and instructional behavior through questionnaires and open-ended email interviews and student achievement for both ensembles and individual student samples via valid and reliable existing measurements. The measurements used to measure student achievement on pre- and post-tests were Smith and Barnes' Orchestra Performance Rating Scale (OPRS-2) for ensembles and Zdzinski and Barnes' String Performance Rating Scale (SPRS) for individual students. The findings suggest that collaboration improved sense of community and teachers' perceptions of professional skill level in self-reported data, but did not impact students' views of teacher instructional skill or 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/en-US/products/dissertations/individuals.shtml.]