The book uses the Summit’s overarching theme and sub-themes as an organizing framework and aligns with the International Ecocity Standards that serve as a diagnostic tool to help cities assess their progress on the path to becoming ecocities. The Ecocity Standards are also proving useful to communities in developing locally relevant pathways to achieving the UN Sustainable Development Goals. The book is presented in four parts that align with the Summit overarching theme of i) building a bridge to socially just and ecologically sustainable cities, supported by sub-themes of ii) climate action, iii) circular economy, and iv) informal solutions for sustainable development. Chapters comprising each part in the book are introduced by a brief precis that orients the reader to the relevant Ecocity Standards that are being addressed and other important contextual considerations that open the potential application of the chapters to an international audience. Arguments presented in the selected papers provide an orientation to the importance of engaging people, where they live, in ecocity transformations as well as emerging opportunities for affordable and accessible technologies that help cities build capacity for implementation of ecocity initiatives.