Information and Communication Technologies (ICTs) are contributing both to environmental problems and to their solution. Will ICT producers, users and recyclers be the major polluters of tomorrow, or will 'Green IT' and a dematerialized information society save the climate? This book provides an in-depth analysis of the relationship between ICT and sustainable development, culminating in 15 recommendations - to producers, users and political decision makers - which show the way to a sustainable information society. Keywords: Information Technology, Environment, Sustainable Development, Environmental Informatics, Green IT, Green Computing, Data Centers, Energy Efficiency, Resource Productivity, Dematerialization, Life Cycle Assessment (LCA), E-waste, Waste Electrical and Electronic Equipment (WEEE), Recycling, Technological Complexity, Critical Information Infrastructure, Open Standards, Rebound Effect.