The purpose of this study was to investigate the impact of a professional learning intervention on conceptual coherence and inquiry orientation for teachers and leaders participating in a K-12 Mathematics Committee (N = 18). This 9-month mixed methods single case study, conducted during the COVID-19 pandemic, was designed using the principles and practices of improvement science and the tenets of the Internal Coherence Framework. Committee sessions focused on understanding research, building capacity with the Standards for Mathematical Practice, and using small groups to analyze teaching and learning artifacts. Methodology included pre- and mid-intervention surveys, entrance and exit tickets, archival documentation, and interviews. Data confirmed a high level of implementation fidelity and a strong positive reaction to the professional learning intervention. Data affirmed that the professional learning intervention helped to cultivate an inquiry orientation as related to committee learning activities. Findings also indicated that as a community of learners, participants came to understand data differently and value data-informed practice. Enhanced awareness and knowledge of the Standards for Mathematical Practice were developed, and recognition of the need for an approach to mathematics education that is more engaging and vertically articulated emerged. As a result of the intervention, initial readiness for solving the problem of practice was created by honoring the internal locus of expertise of members of the committee and creating conditions to be curious and vulnerable with their practice. [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.]