Compliance with laws making certain environments smoke free has focused mainly on smokers' behavior, while the role of non-smokers has scarcely been investigated. Our cross-sectional study interviewed 4043 adults (2037 smokers and 2006 non-smokers) in the general population of Greece during April 2009. Non-smokers reported that they would actively work for compliance with the law. The non-smokers were older, more educated (odds ratio, OR 1.4), and were more likely to be annoyed by the smell of environmental tobacco smoke (OR 2.4) or report that it irritates their eyes (OR 1.8). Policymakers should evaluate how non-smokers could actively support smoke-free laws through reporting of violations using media campaigns that inform them of their rights, and other measures.