Int. J. Environ. Res. Public Health 2011, 8 4. Discussion 429 This study used nationally representative samples of current and former smokers from Canada, the US, the UK, and Australia to examine socioeconomic and national variations in the prevalence, introduction, retention, and removal of smoke-free policies in indoor environments, including private homes, worksites, and local bars and restaurants. The data indicate that smokers with higher SES are more likely to have, introduce, and retain total smoking bans in the home. Current smokers with higher SES were also more likely to have a total smoking ban in the workplace; however, the rate of smoke-free policy adoption in the workplace was comparable by SES group. No consistent association was observed between SES and any smoke-free policies among former smokers, or in bar and restaurants policies among current smokers. The implications of these findings are two-fold. First, the impact of recent efforts to expand the proliferation of smoke-free policies in bars and restaurants in these four countries has been seemingly uniform across those serving different socioeconomic groups; although smoke-free workplaces have previously been more common in high SES occupations, this disparity appears to have disappeared. On balance, the evidence indicates that smoke-free policies in public places are not being implemented differentially by the socioeconomic status of smokers. Among continuing smokers, multivariate analyses indicate a clear and consistent relationship between higher SES and both the presence and introduction of smoking bans in the home. Given the potentially central role that smokers have in determining the smoke-free status of their home, this suggests some reluctance by lower SES smokers to be subjected to home smoking bans. This finding may be a consequence of having a higher likelihood of smokers in their social circle, limited access to outdoor smoking areas, and/or greater overall deprivation [22]. The present findings also indicate that nicotine dependence and attitudes toward smoke-free public environments are strong predictors of policy presence, introduction, and removal among continuing smokers, irrespective of SES. These findings are consistent with that of Borland et al. [8] and provide an evidence base for ongoing and future efforts to promote smoke-free homes, which have previously been shown to substantially reduce secondhand smoke exposure [2] and to have a beneficial impact on smoking behavior [9-11]. More specifically, strategies to enhance smoke-free home adoption should concentrate on the provision of cessation services and initiatives to further denormalize tobacco. The implementation of such strategies would be particularly beneficial in the UK, which had the lowest proportion of smoke-free home prevalence and retention; however, this finding was not surprising considering that the UK has traditionally lagged behind Canada, the US, and Australia in smoke-free policy implementation and support [8,34,36]. Nonetheless, it is important to note that the UK had the highest rate of smoke-free home policy introduction among continuing smokers between Waves. While this study used parallel methods to explore predictors of smoke-free policies in various environments, care needs to be taken in interpreting the results. Although smokers are likely to have a significant role in determining the smoke-free status of their home, the same is not true for public environments. Smokers can choose to avoid environments with restrictions they dislike; therefore, sociodemographic predictors may reflect selective choice of venue for worksites, restaurants, and bars rather than, or as well as, the propensity of proprietors to differentially impose bans based upon their clientele. Nonetheless, the finding that SES is not such a factor among smokers is reassuring.