Data were obtained from Canada's Alcohol and Other Drug Survey conducted by Statistics Canada. To create the sample for telephone interview, each of Canada's 10 provinces was divided according to metropolitan and nonmetropolitan areas. Telephone interviews were completed with 12,155 persons, a response rate of 75.6 percent. Responses were weighted to increase their representativeness for the national adult population. Non-users and those with different patterns of cannabis use could be distinguished by age and gender; by the use of alcohol, tobacco, and other drugs; and by 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 authors conclude that the association between regular cannabis use, heavy drinking, and other risk behaviors poses challenges to prevention and harm reduction initiatives. 20 references and 3 tables