Although interest in ESE policy studies is on the rise, we argue there is a gap in scholarship about the nature and extent of interactions between policymakers and researchers in the ESE field. This paper addresses this gap by discussing one example of such interaction -- an ongoing research-practice partnership (RPP) between the New York City Department of Education Office of Sustainability and Teachers College, Columbia University. Using qualitative document analysis, we -- a researcher and two policymakers -- make two contributions to the literature. First, we analyze the emergence of the partnership and point to the importance of trust, social relationships, and production of local and relevant knowledge. Second, we demonstrate how policymakers use knowledge produced in the RPP to inform specific programmatic decisions (instrumental use) and to clarify assumptions about the system (conceptual use). We also show how engagement with research informs participants' views towards improving school engagement with ESE. Implications for furthering research-policy relationships in ESE include: supporting comparative and longitudinal research designs, giving more attention to the socio-political context shaping partnerships, investigating other forms of knowledge use in RPPs, and reflecting on the politics and priorities given to conducting research with policymakers that demonstrate contributions to the collective good.