This is the 31st edition of the "KIDS COUNT Data Book." The Annie E. Casey Foundation has published this comprehensive assessment of the well-being of children in the United States every year since 1990, during periods of growth and recession and in times of relative prosperity and great anxiety. But since the Foundation began publishing the Data Book, there has never been a year like this. Undoubtedly, because of the COVID-19 pandemic, the world will remember 2020 as a year of fear, pain and loss for everyone, including children old enough to recall what happened long after this time is behind. The crisis has overwhelmed states and communities and has decimated the health and economic stability of families, with a profoundly disparate effect on people of color. This "Data Book" provides the information on child well-being as it stood before the pandemic to help inform the work of the policymakers, researchers and advocates who depend on this regularly published report. [For the "Kids Count Data Book, 2019: State Trends in Child Well-Being," see ED596239.]