This report provides a summary of drug use trends from a survey of nearly 50,000 eighth-, tenth-, and twelfth- grade students nationwide. It also includes perceived risk, personal disapproval, and perceived availability of each drug by this group. A synopsis of the methods used in the study and an overview of the key results from the 2006 survey follows an introductory section. Next is a section for each individual drug class, providing figures that show trends in the overall proportions of students at each grade level (a) using the drug, (b) seeing a "great risk" associated with its use, (c) disapproving of its use, and (d) saying that they could get it "fairly easily" or "very easily." Drugs covered include: any illicit drug use, marijuana, inhalants, LSD, crack cocaine, amphetamines, methamphetamines and ice, heroin, other narcotics, tranquilizers, sedatives (barbituates), ecstasy and other club drugs, alcohol, cigarettes, smokeless tobacco, and steroids. Annual trends are provided for 8th and 10th graders from 1991-2006, and for 12th graders from 1975-2006. These represent the years for which data on each grade are available. The tables at the end of this report provide the statistics underlying the figures; they also present data on lifetime, annual, 30-day, and (for selected drugs) daily prevalence. Among the findings are that 8th graders have been the first to show turnarounds in illicit drug use: they were the first to show the upturn in use in the early 1990s and the first to show the decline in use after 1996. They now appear to be the first showing an end to many of the declines observed in recent years, leaving the 12th graders as showing further declines for the most part. The report also addresses the "cohort effects" phenomena; "cohort effects" refers to lasting differences between class cohorts that stay with them as they advance through school and beyond. (Contains 13 tables.)