In any professional setting, networks flourish spontaneously: human nature, including mutual self-interest, leads people to share ideas and work together even when no one requires them to do so. By building network infrastructures, assigning “leaders” to focus discussion, and combining hierarchy and collaboration to bring together natural professional communities, formalized networks serve as an organizing structure for collaborative professional work. They can replace cumbersome and outdated matrix structures, facilitate the creation and sharing of proprietary information and knowledge, and help build more and better personal relationships among the members of a community. Most important, they can enable leaders to apply the energy of diverse groups of professionals and managers to realize collective aspirations.