The concept of open innovation was introduced by Henry Chesbrough in 2003 and refers to firms' use of inflows and outflows of knowledge to improve innovation processes. The concept has received considerable scholarly attention, but most research has focused on how manufacturing firms can manage inflows of knowledge during their product innovation processes. How outflows of knowledge can be managed by service firms during their innovation processes has until now not received the same scholarly attention. In this chapter, we therefore aim to contribute in filling this knowledge gap by observing an innovation project in tourism during its implementation. The findings suggested that tourism firms reveal different types of knowledge to other tourism firms in non-pecuniary outbound open innovation processes. In this case the knowledge was revealed in joint workshops where several firms participated and in bi-lateral meetings between two firms, and sometimes the knowledge was transferred via consultants or researchers that acted as "knowledge mediators". The findings also suggested that tourism firms decided to reveal knowledge to other firms to improve their image, increase the market size and to sharpen up their own business. Implications for management as well as the need for further research are discussed in the chapter.