We explored how various contextual resources accumulated over multiple years operated together to facilitate a team of high school teachers' sustained and agentive learning after a 4-year research-practice partnership (RPP) grant concluded. Specifically, we examined constellations of resources that promoted the co-evolution of the teachers' collective inquiry in the professional learning community (PLC) and classroom instruction, focused on supporting students' scientific explanations. We qualitatively analyzed the video/audio recordings of the PLC members' interactions in eight 75-min PLC meetings (11 h) and a full-day professional development (8 h) and classroom teaching (34 lessons) over the period of 6 months. We found that the contextual resources accumulated from the historical 4-year RPP--including a culture of collaborative inquiry, collegial relationships, structures for teacher collaboration, and expertise embedded in individuals as well as co-developed tools and practices ("cultural, social, structural, and expertise resources")--were important. These resources, in combination with emerging teacher leadership ("leadership resource") and timely supports, such as school leadership and district-based funding for sustaining structures for collaboration ("leadership and structural resources"), enabled the teachers to launch and drive their own collaborative inquiry and shift instruction after the conclusion of the grant. The harmonized contexts led the teachers to learn across the PLC and classrooms by engaging in co-evolution mechanisms--setting goals based on classroom data, reasoning about instructional practices using various representations of teaching, and experimenting on a set of common practices across classrooms. This paper is part of the special issue on Teacher Learning and Organizational Contexts.