The period of young adulthood (here defined as late teens to age 30) is particularly important because it has tended to be the period of peak use for many drugs. The Monitoring the Future study design calls for biennial follow-ups - through age 30 - of a subsample of the respondents in each participating senior class, beginning with the class of 1976. In 2005, representative samples of the graduating classes of 1993 through 2004 (corresponding to modal ages 19 to 30) provided the panel data - 12 classes in all. Because the questionnaire forms are the same for 12th grade as for each of these follow-ups, it is possible to integrate the data across the 12-year age band. Comprehensive results from this young adult population are presented in this Volume II. After age 30, the class cohorts are followed up at five-year intervals - to date at ages 35, 40, and 45 - using somewhat different questionnaires. Prevalence and trend data for these older ages are also presented here, but for considerably shorter time intervals because of the nature of the study design. Two chapters in this Volume II present data specifically on college students. Trend data are provided since 1980, the first year that a national sample of college students one to four years past high school was available from the follow-up survey. College students have not usually been well represented in national household surveys, because many college students live on campus in group dwellings (dormitories, fraternities, and sororities) that often are not included in household surveys. (The National Household Survey on Drug Abuse, conducted in earlier years by the National Institute on Drug Abuse and now by the Substance Abuse and Mental Health Services Administration, was revised in 1991 to include such group dwellings. That survey is now called the National Survey of Drug Use and Health.) Twenty-six Monitoring the Future surveys on substance use among American college students have now been completed. (Extract of the publication)