This paper explores enabling conditions for scaling high-quality project-based learning (PBL) to understand factors that influence how PBL spreads, whether and how it can be sustained and the extent to which it informs meaningful change in schools. We report on a year-long collaboration across three research projects. Each project team analyzed qualitative data from their individual project and then aggregated data across projects to understand similarities and variations in conditions that support the long-term implementation goals of PBL. We used systems mapping as a methodological tool and a case study approach to test and refine the map. We focus on two enabling conditions for PBL that emerged across all contexts: teacher agency and productive disciplinary engagement (PDE). Teachers reported having agency and described making instructional decisions and adapting PBL to support students' needs. PDE motivated teachers to deepen PBL practices. While the studied collaboratory is not the first to pursue shared goals, to our knowledge it is the first to produce research that aggregates knowledge and data across projects. While scaling innovations in schools is complex, the results suggest that certain conditions enable PBL to be implemented with greater depth and can be generalized across contexts. We discuss the implications of this approach for researchers, stakeholders, and practitioners.