The Casey Foundation's "2018 KIDS COUNT® Data Book" warns that the 2020 census is mired in challenges that could shortchange the official census count by at least 1 million kids younger than age 5. This discrepancy would put hundreds of millions of federal dollars at risk and, in doing so, underfund programs that are critical for family stability and opportunity. The "Data Book" also looks at trends in child well-being during a period that saw continued improvement in economic well-being but mixed results in the areas of health, education, and family and community factors. The report includes the Foundation's signature rankings in key areas of child well-being. This year, New Hampshire is at the top of the rankings. [Foreword by Patrick T. McCarthy. For the "KIDS COUNT Data Book, 2017: State Trends in Child Well-Being," see ED582091.]