The broad array of data presented each year in the "KIDS COUNT Data Book" is intended to illuminate the status of America's children and to assess trends in their well-being. By updating the assessment every year, KIDS COUNT provides ongoing benchmarks that can be used to see how states have advanced or regressed over time. Readers can also use KIDS COUNT to compare the status of children in their state with those in other states across several dimensions of child well-being. The 10 indicators used to rank states reflect a developmental perspective on childhood and underscore our goal to build a world where pregnant women and newborns thrive; infants and young children receive the support they need to enter school prepared to learn; children succeed in school; adolescents choose healthy behaviors; and young people experience a successful transition into adulthood. In all of these stages of development, young people need the economic and social assistance provided by a strong family and a supportive community. As the "KIDS COUNT Data Book" has developed over time, some of the indicators used to rank states have changed because weaker measures have been replaced with stronger ones. Consequently, comparing rankings in the 2010 "Data Book" to rankings in past Data Books does not always provide a perfect assessment of change over time. However, the Appendix shows how states would have ranked in past years if the same 10 measures used in the 2010 Data Book had been employed. The table in the Appendix is the best way to assess state changes over time in overall child well-being. Contents of this "Data Book" include: (1) Summary and Findings; (2) National Indicator Maps: State Rates; and (3) KIDS COUNT Data Center. Also included are: (1) Appendix: Multi-Year State Trend Data for Overall Ranks; (2) Definitions and Data Sources; (3) Criteria for Selecting KIDS COUNT Indicators; (4) Primary Contacts for State KIDS COUNT Projects; and (5) About the Annie E. Casey Foundation and KIDS COUNT. (Contains 3 tables.) [For "KIDS COUNT Data Book, 2009: State Profiles of Child Well-Being", see ED506286.]