Within the entrepreneurship literature, there is a growing interest in understanding collective entrepreneurial approaches to tackling societal challenges. In this study, we examine the orchestration of collective action in an open social innovation project bringing together public administrations, citizens and organized civil society to collaboratively address several societal challenges. Analyzing data generated in-situ and in real-time over the entire duration of the project we show how social impact orchestration can generate impact through four pathways: lead user focus, solution focus, problem focus, and ecosystem focus. For each pathway, we show how orchestration enhanced the impact potential of stakeholders involved by enabling learning and scaling. Our study contributes to the literature on impact entrepreneurship and advances knowledge on orchestrating innovation for social impact.