Trend data show that while the numbers and proportions of undereducated youth are falling, undereducation in the eighties, especially among minority youth, is considerable and persistent. This study uses a population-based definition of undereducation for which trend data are available for Whites and Blacks, beginning in 1967, and for Hispanics in 1973. Undereducated youth are youth, ages 16 to 24, who were not enrolled in school between February 1 and April 1, 1980, and had not completed 12 years of schooling. The study is part of an on-going analysis of the information on young people in the 1980 Census in the context of trend data through 1985. Each of the following analyses of undereducated youth is succinctly reported, using tables, graphs, and brief text, and entitled: (1) Gender; (2) Racal/Ethnic Groups; (3) Place of Birth; (4) Language Background; (5) Poverty Level; (6) Poverty and Race/Ethnicity; (7) Place of Birth and Language; (8) Comparing Years of Schooling; (9) Levels of Schooling and Race/Ethnicity; (10) Status in the Labor Force; (11) Comparing the States; (12) Numbers by State; (13) Rates by State; (14) Asian and Pacific Island Youth; (15) Undereducation Rates in the States; (16) Black Youth: Undereducation Rates in the States; (17) Hispanic Youth: Undereducation Rates in the States; (18) Native American Youth: Undereducation Rates in the States; (19) White Youth: Undereducation Rates in the States; and (20) White Language Minority Youth: Undereducation Rates in the States. Terms used in the analyses and two key tables of statistical data on out-of-school youth are appended. (FMW)