Office design has been demonstrated to influence knowledge sharing within (large) organizations located in single-tenant buildings. For business centres, where organizations share spaces, facilities and services, it is often assumed that social networking and knowledge sharing between organizations occur even more frequently. However, empirical research with regard to the effects of the physical design of business centre offices on social networking and knowledge sharing behaviour is still limited, despite the growing number of business centres. Therefore, the purpose of this research is to analyse the effects of the physical work environment on perceived social networking and knowledge sharing behaviour within and between organizations in business centres. Data collected among 268 users of 53 business centres in the Netherlands was analysed using path analysis. Results showed that using a lounge room is most effective for knowledge sharing between organizations. Moreover, meeting spaces and flexibly used workspaces appear to be important for knowledge sharing within organizations.