["Journal of Economic Surveys, EarlyView. ", "\nABSTRACT\nOpen‐source innovation refers to an ecosystem‐based innovation paradigm in which innovators use accessible technological resources to support innovation. For latecomer innovators, it offers a low‐cost pathway to overcome technological constraints and pursue catch‐up with established leaders. Drawing on affordance theory, we propose a conceptual framework to explain how open‐source innovation facilitates latecomer catch‐up. Our framework develops the foundation and mechanisms of open‐source innovation. The foundation highlights the incubating effect, through which open‐source innovation reshapes latecomer innovators’ starting points. The mechanisms include technology completion and resource synergy as two dynamics, with innovation willingness as a boundary. Further, we conduct a survey of specific latecomer innovators in China, and the majority of respondents agree with the framework's key dimensions. Accordingly, we suggest the rationales and limitations of the conceptual framework. This study advances the understanding of open‐source innovation and offers implications for latecomers and policymakers.\n"]