The Collaborative for Academic, Social, and Emotional Learning (CASEL) has produced a series of briefs documenting insights from their efforts to understand how educators and researchers can build relationships that support a shared action research agenda around social and emotional learning (SEL). This five-part series shares the perspectives of researchers and practitioners on developing and sustaining collaborative inquiry in classrooms, schools, districts, and states. The goal of the series is two-fold: (1) to articulate an overview of CASEL's research-practice agenda; and (2) to explore our learnings at the school, district, and state level about developing research-practice partnerships (RPPs), action research, continuous improvement, and adult SEL capacity. The Lowell Community School in Massachusetts research-practice partnership (RPP) aims to better understand how to support teachers in integrating social and emotional learning (SEL) in academic instruction, particularly during early elementary math classes. This partnership also explores how teachers can leverage SEL in their classrooms to build equitable learning spaces and conditions for their students. This brief highlights three key insights related to establishing a successful RPP: (1) Researchers must be flexible and communicate regularly when establishing an RPP project with school staff; (2) Trust between the researcher and school staff is foundational in building a research-practice partnership; and (3) For a successful school-level research-practice partnership, school leaders must be prioritized as key levers.