Book excerpt: The world’s population is currently undergoing a significant transition towards urbanisation, with the UN expecting that 70% of people globally will live in cities by 2050. Urbanisation has multiple political, cultural, environmental and economic dimensions that profoundly influence social development and innovation. This fundamental long-term transformation will involve the realignment of urban society’s technologies and infrastructures, culture and lifestyles, as well as governance and institutional frameworks. Such structural systemic realignments can be referred to as urban sustainability transitions: fundamental and structural changes in urban systems through which persistent societal challenges are addressed, such as shifts towards urban farming, renewable decentralised energy systems, and social economies. This book provides new insights into how sustainability transitions unfold in different types of cities across the world and explores possible strategies for governing urban transitions, emphasising the co-evolution of material and institutional transformations in socio-technical and socio-ecological systems. With case studies of mega-cities such as Seoul, Tokyo, New York and Adelaide, medium-sized cities such as Copenhagen, Cape Town and Portland, and nonmetropolitan cities such as Freiburg, Ghent and Brighton, the book provides an opportunity to reflect upon the comparability and transferability of theoretical/conceptual constructs and governance approaches across geographical contexts. Urban Sustainability Transitions is key reading for students and scholars working in Environmental Sciences, Geography, Urban Studies, Urban Policy and Planning.