In 2000, the National Household Survey on Drug Abuse asked youths aged 12- to 17-years-old to report how they thought their parents would feel about their trying marijuana/hashish once or twice, having one or two drinks of an alcoholic beverage nearly every day, or smoking one or more packs of cigarettes per day. Of the estimated 23 million youths in the United States, the majority thought their parents would strongly disapprove of their substance use. Rates of substance use among youths were lower among those whose parents disapproved of substance use than among those whose parents did not disapprove. Youths that were younger, female, or Asian were more likely to think that their parents would strongly disapprove of their substance use compared with youths that were older, male, or from other racial/ethnic groups. The survey also asked about use of marijuana/hashish, alcohol, and cigarettes during the month before the survey. The rate of past month use was lower among youths that believed that their parents would strongly disapprove of their substance use compared with rates among those that through their parents would somewhat disapprove or would neither approve nor disapprove. 1 table, 4 figures, 2 endnotes