This paper extends tertius iungens social network dynamics to theorize the micro-social level of entrepreneurial activity – the social dynamics of relatively small numbers of actors surrounding the formation and early growth of new ventures. We animate these ideas with a focus a project-based view of entrepreneurship that emphasizes the collective action in which initial entrepreneurial groups define emergent goals and aggregate people and resources toward realizing them. This theoretical framework has as its central conceptual components tertius iungens connecting activity and creative project action trajectories. Our perspective offers insights into the social processes associated with new venture formation while integrating and extending key elements from a growing body of work on entrepreneurial action. By illuminating the initial stages of emergent entrepreneurial action, our study clarifies social processes surrounding new venture initiatives while suggesting ways to advance entrepreneurship theory going forward.