This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book analyses the procedural side of sustainability it offers a new perspective on the implementation of sustainability that will be useful and attractive to both planning professionals and academics. It focuses on the recognition that planning solutions for sustainability cross three arenas: the social arena, the environmental arena and the urban economic arena. The book analyses to what extent planning innovations can be transferred from one context to another. It describes the term sustainable planning to acknowledge that a planning solution implies trade-offs between the three arenas of sustainability. The book provides the understanding of factors facilitating the implementation of sustainable solutions in planning practice. It focuses on previous pioneering works studying sustainability and its relationship to cities.