The science behind entrepreneurial ecosystem building is still in its early stages and remains short on evidence-based methodologies and metrics for success. Research on effective practices requires robust data, but the ecosystem building process is complex. Its nonlinear, multidimensional solutions are difficult to track with common economic development measures, especially in the short term. New, more effective metrics and a shared research agenda that capture the early work of ecosystem building would allow for rigorous data collection and faster feedback loops. Ecosystem builders and researchers will use data to identify the most effective strategies and tactics and to better inform their communities about the effectiveness of their work. Ultimately, a shared system of metrics and measurement, coupled with new collaborative research agendas focused on developing evidence-based ecosystem building methodologies, would allow us to determine the most impactful principles and practices to enable entrepreneurship at scale.