This chapter gives an overview of the objectives of the book, presents its structure, and summarizes the content of each section and chapter. It introduces planetary well-being as a novel cross-disciplinary concept coined to foster global transformation to a more inclusive and equal expression of well-being for all. The chapter describes how researchers from different human, social, and natural sciences apply and reflect on the concept of planetary well-being in this book, demonstrating its value as an interdisciplinary and cross-cutting driver of change. The Introduction concludes that sustainability science and policy need a concept of well-being that is built on systemic and non-anthropocentric grounds.