This article discusses the impact of a year long professional development on high school mathematics teachers' concerns regarding the implementation of graphing calculators in their classrooms. Teachers' concerns were assessed at the beginning and end of the yearlong professional development using the Concerns Based Adoption Model Stages of Concern Questionnaire. Results show that high awareness, information, and personal stage concerns were prevalent at the beginning and end of the professional development experience. Growth in management and refocusing stage concerns did occur as a result of the professional development. These results demonstrate that integrating graphing calculators in the curriculum is time consuming and suggests that professional development can help teachers make this instructional change over time. Additional sustained and targeted professional development that addresses personal, management and consequence Stages of Concern are needed for graphing calculators to become more fully integrated in these teachers' classrooms. Recommendations on how to accomplish this task are explored. (Contains 5 tables.)