The Leaf Plan. Towards the Ecological Transition presents innovative methodologies and practices to guide and support a sustainable urban development to cope with climate, social, economic changes. The book will illustrate comprehensive design approaches to address climate change, urban metabolism, temporary uses, landscape multifunctionality, cohabitation through new modes of urban design based on criteria of flexibility and adaptability. Trento is the experimental territory where the innovative process, methodologies and theoretical reflection have been tested above the framework of the three-year research project "TUT Trento Urban Transformation". The book is structured around the five challenges (Ecological, Accessible, Smart, Welcoming and Beauty) proposed by the TUT research group for the Trento Leaf Plan, the new metabolic plan for the city of Trento. Beside the innovative field-test experimentations, the holistic methodological approach proposed by the book will be transferable and adapted in other metropolitan contexts to enhance the urban ecological transition. The publication, edited by the TUT research group, will include theoretical essays, critical selection of reference projects, operational tools, and interviews with experts in ecological transition, sustainable mobility, co-design approach, sharing, and urban resilience.