Each year since 1990, the Annie E. Casey Foundation has published the KIDS COUNT Data Book to track the well-being of children nationally and in every state. When the first Data Book was launched 25 years ago, the hope was that it would raise public awareness and build public commitment to invest in solutions to ensure that each and every child has the opportunity to thrive and to reach his or her full potential. In partnership with a network of state and national advocates for children, the foundation wanted to help local communities, states, and national leaders make better informed policy and practice decisions to improve the economic, health, educational, family, and community well-being of America's children. The Casey Foundation has used the KIDS COUNT Data Book to raise awareness locally and nationally about how kids are doing and what policies and programs might lead to improvements. In the quest to improve outcomes for the nation's children, the Data Book was used to highlight critical building blocks of healthy child development. Special emphasis has been placed on:?? (1) the importance of child well-being to the nation's future prosperity, global competitiveness, and community strength; (2) ??the variability in child well-being by income, race, ethnicity, and geography; and (3) ??evidence-based policies, programs, and practices that work. The following sections take a look at the demographic, social and economic context for changes affecting children as well as major trends in child well-being since 1990 in each of the four domains covered by the KIDS COUNT index: (1) Economic Well-Being, (2) Education, (3) Health and (4) Family and Community. Key policies that have contributed to improvements in child well-being as well as daunting challenges that remain are identified. Appended are: (1) Child Well-Being Rankings; and (2) Data for 16 Indicators of Child Well-Being.