In a national survey conducted in 1994, 29.3% of all respondents reported that they had used cannabis at least once, 7.3% reported using at least once during the year of the survey, and 2.0% reported using cannabis at least once a week during the year of survey. Nonusers and those with different patterns of cannabis use could be distinguished by age; gender; the use of alcohol, tobacco, and other drugs; and involvement with drug users. Frequent cannabis use at the time of the survey was associated with "heavy" drinking and drinking problems, drinking and driving, driving within 2 hours of using cannabis, and the use of other drugs, especially among young males. The association between regular cannabis use, "heavy" drinking, and other risk behaviors poses challenges to prevention and harm-reduction initiatives.