Book excerpt: What were new ideas 30 years ago, such as the concepts of participatory development and systems thinking, are now accepted norms in international development circles. The majority of professionals engaged in rural development accept the proposition that the people who participate in development should play an active role in defining, implementing, and evaluating projects intended to improve their productivity and lives. However this goal remains unrealized in many development programs. Harnessing the Power of Collective Learning considers the challenges and potential of enabling collective learning in rural development initiatives. The book presents 11 case studies of organizations trying to develop and implement collective learning systems as an integral component of sustainable development practice. Through systematic reflection on action and experience, key lessons and themes emerge regarding the nature of voice, participation, feedback loops, accountability and transparency, that will be useful for many others in the development community. This book is a useful resource for academics, practitioners and policy makers in the areas of international development, sustainable development, organizational development, philanthropy, learning communities, monitoring and evaluation and rural development.