The Adaptation Gap Report 2021 – its sixth edition – is part of a new set of reports launched in 2020 in the run up to the 2023 Global Stocktake. It is structured in three parts: Part I (chapters 3 to 5) assesses national and global progress on adaptation, covering three central elements of the adaptation process: planning, financing and implementation. This part has formed part of each AGR edition and indicates the status and trends of the global adaptation process. Over time, the reports will provide a cumulative record of progress. Part II (chapter 6) presents a deep dive into the three elements of part I but focuses on a particular theme or sector of society. The purpose of this deep dive is twofold: first, it provides a more detailed picture of progress in a selected focus area; second, it adds additional perspectives, nuance and detail to the overall assessment of progress contained in the report. Part III (covered in chapters 2 and 7) introduces a framework for understanding global progress on adaptation, thus guiding the reader through the analysis of the report, and synthesizes the findings described in Parts I and II to provide an overview of global progress on adaptation. Chapter 7 also provides an overview of future developments and outlines the challenges ahead and intended future work towards improving the assessment of global adaptation.