This study investigated concerns and perceptions about the implementation of a professional learning community at the high-school level. The No Child Left Behind Act requires schools to be accountable for increasing the achievement of all students. The school reform model researched in this study is the concept of a professional learning community (PLC). A PLC establishes a framework in which teachers commit to working in collaborative teams to accomplish high levels of learning for all students (DuFour & Eaker, 1998). A mixed-method research design was used in this study to test the three research questions, focusing on the concerns of implementing a PLC at the high-school level. The quantitative survey data were collected from 100 core (English, math, science, and social science) and non-core instructors at a high school in a suburban community in North Dakota, utilizing the Stages of Concern Questionnaire (SoCQ). The qualitative survey was constructed based on results from the SoCQ and was administered to 13 department chairpersons at the same high school. Study participants were asked to identify their years of teaching experience and if they were a core or non-core instructor. The results of the quantitative statistical analysis indicated that, regardless of years of experience, the stage of concern that was the highest was Stage 0 (Awareness). Awareness indicated that the respondents had little concern about the innovation. Likewise, core and non-core teachers also rated Stage 0 as the highest concern stage. The qualitative responses indicated that, at the time of implementation, the purpose of PLCs was not made clear. In addition, it was reported that many teachers were unsure what to do with the time. Additional responses indicated that many staff members feel comfortable with the innovation and have practiced the concept of a PLC in the past. The concept of a PLC holds great promise for the improvement of schools and results. The model of a professional learning community is simple in definition, yet complex in implementation and execution. The process of identifying professional development for a successful transition to adopt and practice the fundamentals of a professional learning community is paramount.