While much progress in curtailing exposure to environmental tobacco smoke has occurred in Ontario, many jurisdictions still do not have any restrictions on smoking. To assess support in Ontario for restrictions, and recent changes in knowledge, attitudes, and behavior, we compared the findings of a population-based telephone survey conducted in 1991 (n = 1421) to those of a similar survey conducted in 1983 (n = 1383). Increases were found in the population's reported knowledge of specific health effects. Marked changes occurred in attitudes to restrictions on smoking. In 1991, the population consistently favoured more restrictions on smoking and their enactment by all levels of government. A role for local health departments in enforcement was clearly recognized. Most smokers indicated that they would comply with more restrictions. We also found that the self-reported prevalence of smoking had decreased 8 percentage points between 1983 and 1991. Population-based evidence of strong and increasing support for restrictions, accompanied by predictions of a high level of compliance, especially by smokers themselves, should facilitate legislation aimed at further curtailing smoking.