Background: substantial research on reform implementation highlights numerous challenges to implementing innovations at scale with depth and sustainability, yet new reforms continue to encounter many of the same challenges. This has led to calls for researchers to work in partnership with practitioners to design, implement, and scale educational innovations. Although these approaches hold promise, little is known about the internal operations of these improvement approaches and the experiences of their participants. Purpose: through a case study of a research-practice partnership that uses a continuous improvement approach to design and development, this article explores how the collaborative design process shaped the resulting innovation design. Research design: this is a qualitative case study that included interviews with members of the district and school design teams, observations and field notes from design team meetings, and participant feedback forms. Findings/results: the evidence converges on three main challenges in the design process. These challenges point to tensions in maximizing all the design factors because they sometimes conflicted with each other: (1) members were most engaged when the work was very specific and deemed feasible in a particular context, (2) efforts to develop more specificity in the design emphasis were limited by efforts to engage educators in a collaborative process in which school-level actors had ownership over key design decisions, and (3) the abstractness of the emerging reform led to difficulties in establishing a shared deep understanding of each core component of the reform. Finally, the ability of school teams to productively resolve these tensions was related to the existing capacity of the school. Conclusions: this case study of a collaborative design process in a research-practice partnership illustrates the complexities of the co-construction of a set of reform practices between researchers, practitioners, and other stakeholders and highlights the need for a delicate balance between specificity of the design and local engagement. We showed how a collaborative process fostered high engagement as researchers and practitioners co-constructed the reform, and how the team struggled to define the core strategies in sufficient detail to allow for implementation planning in a way that maintained the co-constructed design. There appeared to be a tension between achieving the necessary concreteness or specificity in the reform design that would be implemented across contexts, and a process that valued local ownership and collaborative decision-making. 2020 Teachers college, columbia university. All rights reserved.