School-university partnerships also known as professional development school (PDS) partnerships provide potential for universities and schools to establish partnerships that can benefit university faculty, school teachers, university students, and school students. This study examines the impact of a PDS partnership in which the author served as a school-based mathematics coach for two years in a high-need elementary school. Data sources included interviews, surveys, and field notes from classroom observations. Inductive qualitative analyses which were situated in a multi-level framework for researching professional development found that teachers posed more cognitively demanding mathematical tasks and high-level questions in year two compared to year one of this project. Further, student achievement was noted on both state-wide and district-created assessments. Also teachers reported that the school-based approach to professional development led to some teachers taking on more informal leadership roles to support their colleagues' mathematics instruction. Implications for school-based learning opportunities across the world include the need to establish specific university-school partnerships, and carefully designing research studies to examine the impact of these learning opportunities.