Each year, the Foundation for Child Development and the Child and Youth Well-Being Index Project at Duke University issue a comprehensive measure of how children are faring in the United States. The overall comprehensive Child Well-Being Index (CWI) is based on a composite of 28 Key Indicators of well-being that are grouped into seven Quality-of-Life/Well-Being Domains. These domains are: family economic well-being, safe/risky behavior, social relationships, emotional/spiritual well-being, community engagement, educational attainment, and health. This year's overall CWI is an updated measure of trends over the 34-year period from 1975 to 2009, with projections for 2010. The major trends that can be drawn from the 2011 overall CWI Update include: (1) Progress in American children's quality of life has essentially stalled; and (2) On average for all American children and youths under age 18, all of the improvements in economic well-being of families with children under the age of 18 over the past 35 years have been lost. Appended are: (1) Methods of Construction and Indicator List for the CWI; (2) Sources of Data for the CWI; (3) Child and Youth Well-Being Index Values, 1975-2008, with Projections for 2009-2010; and (4) Long-Term Changes in the CWI Domains and Key Indicators. (Contains 7 figures and 11 footnotes.) [For previous report, "Child Well-Being Index (CWI), 2010," see ED519372.]