Many case studies have been undertaken about how informal, sponsored, and supported communities of practice operate within private and public sector organizations. To date, however, no examination has been made of how informal communities of practice operate within the third sector, the sector of community, and voluntary organizations. The third sector has a long history of using community space, in various forms, either physical or notional, to engage individuals in discourse and informal learning. The rise of the network society has added value to this process by allowing active individuals to personalize networks through the use of technologies which enhance communication. The third sector is now demonstrating that individuals and groups are seeking to create open access knowledge-sharing spaces which attempt to combine face-to-face networks with computer-mediated communications to support informal learning between community development practitioners. This article examines the role of Sunderland Community Development Network in the creation of informal communities of practice. It pays particular attention to three key areas: 1. Community space: How core, active, peripheral, and transactional community spaces within third sector partnerships create an ebb and flow of informal communities of practice. 2. Personalized networking: How issue-based activity, inside and outside communities, can lead to the rapid appearance and disappearance of informal communities of practice. 3. Knowledge-sharing space: How core members of a third sector organization can create a dynamic model of roles within informal communities of practice capable of impacting upon processes of governance beyond the organization.