Teacher's noticing of students' mathematical thinking has been an important focus of research in the past two decades (e.g., Jacobs et al., 2010; Sherin et al., 2011). Noticing matters, but it is not an end in itself (Schoenfeld, 2011). It is operationalized within the context of teachers' dispositions and knowledge which shape decisions teachers make while responding to student thinking and planning the next instructional steps. In order for teachers to adapt productive beliefs about how children learn and shift to student-centered instruction, they need to acknowledge the importance of understanding students' existing conceptions of mathematical ideas (Carpenter & Lehrer, 1999). A professional development (PD) program with a central focus of task-based student interviews can potentially improve their noticing of student thinking. In this study, I report on the experiences of three middle school mathematics teachers who participated in such a program. I used multiple-case study methodology and examined teachers' written responses to video-based noticing prompts as well as their discussions of selected interview clips shown during the PD sessions. The results indicated that teachers initially focused on interviewer actions and over time, attended to and interpreted students' thinking in a more comprehensive manner. This study supported others' findings (e.g., Krupa et al, 2017) that teachers did not score high in responding to students' mathematical thinking. Lastly, my study underlined the critical role of the PD facilitator. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]