Background: Support for smoke-free policies increases over time and particularly after implementation of the policy. In this study we examined whether the comprehensiveness of such policies moderates the effect on support among smokers. Methods: We analysed two waves (pre- and post-smoke-free legislation) of the International Tobacco Control (ITC) surveys in France, Germany, and the Netherlands, and two pre-legislation waves of the ITC surveys in UK as control. Of 6,903 baseline smokers, 4,945 (71.6%) could be followed up and were included in the analyses. Generalised Estimating Equations (GEE) were used to compare changes in support from pre- to post-legislation to the secular trend in the control country. Multiple logistic regression models were employed to identify predictors of individual change in support. Findings: In France, the comprehensive smoking ban was associated with sharp increases in support for a total smoking ban in drinking establishments and restaurants that were above secular trends. In Germany and the Netherlands, where smoke-free policies and compliance are especially deficient in drinking establishments, only support for a total smoking ban in restaurants increased above the secular trend. Notable prospective predictors of becoming supportive of smoking bans in these countries were higher awareness of cigarette smoke being dangerous to others and weekly visiting of restaurants. Conclusions: Our findings suggest that smoke-free policies have the potential to improve support once the policy is in place. This effect seems to be most pronounced with comprehensive smoking bans, which thus might be the most valid option for policy-makers despite their potential for creating controversy and resistance in the beginning.