Numerous districts are implementing Professional Learning Communities (PLCs) as a part of reform efforts to improve student achievement to meet external accountability mandates. Few districts, however, have considered the essential supports and components that teachers working in PLCs require for these teams to result in instructional improvement. This study reports on the work of one mid-sized urban district that attempted to implement and support PLCs in developing essential PLC characteristics, implementing an improvement process, and establishing an instructional goal, research-based practices shown to facilitate improvement. This district also provided professional development to teachers and administrators in the implementation process. Findings from this study affirm the research-based practices on which this district's implementation plan was based, while suggesting that additional school-based conditions also needed to be in place: (1) the provision of school-based professional development on PLCs; (2) a school culture focused on collaboration; and (3) a readiness by school leaders to engage in and communicate expectations for PLC work. The study concludes by recommending that districts consider providing differentiated supports and targeted professional development to schools during their first years of PLC work to ensure growth among all PLC teams.