Innovation has emerged as a central concern in sustainable development and related policy arenas such as climate change. The book explores the implications for policy practice of this new emphasis and the challenges it creates for public, private, and civic actors who want to foster technological innovation as a way to promote sustainable development. We present a set of case studies of success and analyze their implications for practice. We emphasize that innovation extends all the way down to the user and highlight the often unmet demands for institutional innovation this creates. We describe a framework for analyzing these cases that draws out their implications for policy and for action by governmental, non-governmental, and market organizations.