How can action research further new research orientations towards sustainability? This book, empirically situated in the field of upstream public engagement, involving local residents, researchers and practitioners in bottom-up processes deliberating on urban sustainability, answers this question by analysing processes of social learning. The book addresses the need to move towards sustainability at societal level as a democratic challenge questioning the way we live on planet earth. By conceptualising sustain-ability as an immanent and emergent ability of ecological and social life, continuously to renew itself without eroding its own foundation of existence, it argues that since sustainability cannot be invented but only supported (or eroded) by science, we need to reframe science in the role of sustaining sustain-ability. Through analyses of a three year action research programme, aiming to provide local citizens with a greater say in the future of urban sustainability research, this book shows how action research can make important methodological contributions to processes of social learning between citizens and scientists by enabling free spaces in peoples everyday life and within academia, where aspects of un-sustainability can be addressed and new imaginations of more sustainable futures emerge.