Many industrial ecologists have focused upon industrial ecosystems and eco-industrial parks as a key strategy for implementing industrial ecology. Some researchers have emphasized developing networks of by-product exchange among co-located companies. This is one among many options for the greening of industrial park design. This article reviews a range of methods for supporting the creation of exchange networks in new eco-industrial parks. Development teams working with established parks or industrial regions can adapt many of these approaches to these other settings. In either case, a central recommendation is to respect the self-organizing nature of the process and to focus on setting conditions that enhance that process.