Highlights from the 2009 national survey include: (1) an estimated 21.8 million Americans aged 12 or older were current illicit drug users, meaning they had used an illicit drug during the month prior to the survey interview; (2) among youth aged 12 to 17, the current illicit drug use rate increased from 2008 (9.3. percent) to 2009 (10.0 percent); between 2002 and 2008, the rate declined from 11.6 to 9.3 percent; (3) between 2008 and 2009, the rate of current use of illicit drugs among young adults aged 18 to 25 increased from 19.6 to 21.2 percent, driven largely by an increase in marijuana use (from 16.5 to 18.1 percent); (4) slightly more than half of Americans aged 12 or older reported being current drinkers of alcohol in the 2009 survey (51.9 percent); (5) in 2009, an estimated 12.0 percent of persons aged 12 or older drove under the influence of alcohol at least once in the past year; (6) most (85.5 percent) of the 4.6 million past year alcohol initiates were younger than 21 at the time of initiation; (7) in 2009, almost four fifths (77.0 percent) reported having seen or heard drug or alcohol prevention messages from sources outside of school, lower than in 2002 (83.2 percent); and (8) of the 20.9 million persons aged 12 or older in 2009 who were classified as needing substance use treatment but did not receive treatment at a specialty facility in the past year, 1.1 million persons (5.1 percent) reported that they felt they needed treatment for their illicit drug or alcohol use problem. Figures, tables, and appendix