Many organizations have been investing a significant amount of time, energy and resources in overcoming intra-organizational barriers to sharing knowledge. Such barriers prevent individuals who are looking for knowledge from connecting with those who possess it. In this chapter, four common barriers (that the authors have seen in their work with knowledge-based organizations) have been identified that prevent two parties from coming together and sharing knowledge: awareness, access, application and perception. Based on their research and experience, they describe how Communities of Practice can be an important vehicle for breaking through each of these barriers and enabling knowledge to flow more effectively within organizations. In addition, practices are highlighted that organizations can put into place to provide effective support for these communities.