The purpose of this study was to better comprehend the experiences of middle school teachers when they are asked to implement practices promoted in professional development. The professional development in which the teachers were involved centered on cultivating classroom discourse through the use of six Teacher Discourse Moves. These moves were developed to support teachers as they purposefully engage students in mathematical reasoning and justification, and as they position students as people who are capable of making sense of mathematics. Phenomenological methods were used to construct the interview protocol and the analysis of the data. Data sources consisted of semi-structured interviews with twelve participants of the professional development. The interview questions were designed to inquire about the experiences during three stages of classroom practice: pre-implementation, implementation and post-implementation of the practices. The analysis of the interviews resulted in the development of five major themes to capture the essence and to illuminate the teachers' experiences. The themes of analysis were concerns, choices, awareness, reflection, and change. These findings can inform researchers of professional development of the importance of listening to the voices of teachers when studying professional development or such programs. [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.]