Breakthroughs in science and technology increasingly happen outside of firms in informal interorganizational communities of innovators. The effort of a group on a specific topic across firms, expertise, and geography can function as an emergent organizational form, capable of great productivity. Using data from computer science, basic research, and management strategy to identify and study these intense clusters of innovators, or 'knowledge communities,' this book illuminates the new organizational logics that govern such collective success. The interplay between organizational boundaries and interorganizational collaboration reveals interesting and counterintuitive lessons about how science and technology work in practice. These insights fundamentally challenge the centrality of both firm boundaries and geographic clusters for innovation in favor of a decentralized network perspective. Academics seeking to understand innovation in science and technology, allocators of grants and research support, corporate R&D departments, policy makers and NGOs, venture capitalists, and management consultants will all benefit from this original and challenging work.