AbstractSoftware product innovation in large organizations is fundamentally challenging because of restrained freedom and flexibility to conduct experiments. As a response, large agile companies form internal startups to initiate employ-driven innovation, inspired by Lean startup. This case study investigates how communities of practice support five internal startups in developing new software products within a large organization. We observed six communities of practice meetings, two workshops and conducted ten semi-structured interviews over the course of a year. Our findings show that a community of practice, called the Innovation guild, allowed internal startups to help each other by collectively solving problems, creating shared practices, and sharing knowledge. This study confirms that benefits documented in earlier research into CoPs also hold true in the context of software product innovation in large organizations. Henceforth, we suggest that similar innovation guilds, as described in this paper, can support large companies in the innovation race for new software products.