While collaborating with several competitors on coupled innovation projects requires smooth knowledge sharing to ensure the project's success, protecting knowledge is also essential due to the prevailing risks of coalition formation, opportunism, and knowledge leakage. Intense tensions between knowledge sharing and protection may arise and must be managed to avoid project failure. This article explores the formal and informal mechanisms used to manage these tensions. The case studied (Galileo) reveals the limited role of informal mechanisms to manage such tensions and shows how a centralized project structure encouraged the formal sharing of knowledge by protecting firms from unwanted knowledge transfers between competitors.