A growing number of research and development-driven companies are located in knowledge-based ecosystems. Value creation by these ecosystems draws on the dynamics of single firms (interacting and partnering) as well as the ecosystem at large. Drawing on a field study of a Dutch high-tech campus, two key sources of value creation are identified: (1) facilitation of the innovation process for individual companies and (2) creation of an innovation community. Furthermore, the coevolution of the ecosystem's business model with firm-level business models explains why technology-based firms join, stay in, or leave the ecosystem at a certain point in time. A remarkable finding is that ecosystem managers have to deliberately facilitate exit routes for companies that no longer fit the ecosystem in order to enhance and reinforce its business model. As such, this study suggests a dynamic capability perspective on knowledge-based ecosystems that need to develop a business model at the ecosystem level to create sufficient innovative capacity and entrepreneurial fitness.