This study provided insight into the impact a professional development series on cognitively demanding tasks had on teachers’ identification and implementation of tasks, as well as, determined which aspects of the professional development were beneficial to participants’ understanding of cognitively demanding tasks. The professional development included five sessions and was centered on the Instructional Quality Assessment (IQA) Potential of the Task and Implementation of the Task Rubrics (Boston et al., 2019). As part of the study, participants submitted tasks and student artifacts pre and post professional development. The investigation included an analysis of tasks, student artifacts, and a thematic analysis of collaborative conversations and interviews. A single case study was conducted, with the case being the professional development series. Additionally, case participants provided insights on their experiences and learning on cognitively demanding tasks. Findings suggested that there was an impact on participants’ implementation of cognitively demanding tasks after they participated in the professional development series. Throughout the thematic analysis, aspects of the professional development were identified as beneficial to participants’ learning and understanding of cognitively demanding tasks. Discussion of the findings in relation to the current literature and their implications were provided. Additional research was suggested to continue the professional development series with the IQA Teachers’ Questions, Teacher’s Linking, and Teacher’s Press Rubrics (Boston et al., 2019) which follow the IQA progression. Further research into the complexity of schools under heightened state or county supervision should be investigated in regard to professional development and teacher autonomy. These findings add to the literature and research in the field of mathematics education, cognitively demanding tasks, and professional development.