Teacher professional development is key to student learning, making the need for professional development in mathematics stronger than ever. While research has identified some features of professional development that impact teacher and student outcomes, such as sustained duration and a focus on content, there is still much mathematics education researchers do not know regarding which design features are most impactful to learning and how specific features of professional development connect to teacher learning. This project will investigate six prior NSF funded professional development projects looking for features of the professional development associated with teacher uptake and learning. For example, the project will consider how the establishment of community or norms of collaboration support teachers’ long-term classroom practice. This work will contribute to the field’s understanding of professional development success, teacher learning and contextual factors that support or impede the enactment of new learning. <br/><br/>This Discovery Research preK-12, four-year study in the Teaching Strand will investigate six different NSF-funded professional development projects to better understand and contribute to mathematics teacher learning and professional development design theories. Using a mixed method and multi-case methodology the research team aims to understand effective factors associated with uptake, learning and impact for mathematics teachers across six different professional development models. The research questions this project will address are: (1) What is the nature of what teachers take up and use two to five years after participating in professional development workshops?, (2) What factors influence what teachers take up and use, and in what ways?, (3) What design features are associated with teachers’ perceived teacher learning over time?, and (4) How does a professional development’s position on the specified-adaptive continuum affect what teachers take up and use? This work will contribute to theories of mathematics teacher learning and instructional change as well as research-based solutions and recommendations for future mathematics professional development approaches. Data collection includes survey data, simulated recall interviews, semi-structured interviews, and classroom videotaping. Survey data will be analyzed through statistical approaches and interview data will allow for case study development, quantitative and qualitative data will also allow for cross case comparisons. Results will be disseminated through conferences, journals, a project website and social media platforms. <br/><br/>The Discovery Research preK-12 program (DRK-12) seeks to significantly enhance the learning and teaching of science, technology, engineering, and mathematics (STEM) by preK-12 students and teachers, through research and development of innovative resources, models, and tools. Projects in the DRK-12 program build on fundamental research in STEM education and prior research and development efforts that provide theoretical and empirical justification for proposed projects.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.