This report builds upon a series of National Center for Education Statistics (NCES) reports on high school dropout and completion rates that began in 1988. It presents estimates of rates in 2006, provides data about trends in dropout and completion rates over the last 3 decades (1972-006), and examines the characteristics of high school dropouts and high school completers in 2006. Four rates are presented to provide a broad picture of high school dropouts and completers in the United States: (1) Event dropout rate estimates the percentage of high school students who left high school between the beginning of one school year and the beginning of the next without earning a high school diploma or its equivalent (GED); (2) Status dropout rate reports the percentage of individuals in a given age range who are not in school and have not earned a high school diploma or equivalency credential, irrespective of when they dropped out; (3) Status completion rate indicates the percentage of individuals in a given age range who are not in high school and who have earned a high school diploma or equivalency credential, irrespective of when the credential was earned; and (4) Averaged freshman graduation rate estimates the proportion of public high school freshmen who graduate with a regular diploma 4 years after starting 9th grade. Findings are presented demographically overall, by sex, race/ethnicity, family income, age and region. Two appendixes are included: (1) Technical Notes and Glossary; and (2) Standard Error Tables. (Contains 36 footnotes, 4 figures and 25 tables.)