Int. J. Environ. Res. Public Health 2010, 7 2790 diffusion of tobacco use into four distinct stages. The last stage is characterised by a decrease in the prevalence of tobacco use for both men and women but an increase in tobacco-related mortality among women due to the lag between tobacco use and tobacco-related mortality. Another important feature of the diffusion of the epidemic is the widening of socioeconomic differences in the context of smoking prevalence. In the early stages of the process, smoking prevalence was higher in upper socioeconomic groups. Today, however, this trend has reversed, resulting in major socioeconomic inequalities in terms of both smoking prevalence and smoking-related morbidity and mortality. Smoking has been identified as a primary cause of inequalities in death rates between different social classes [2]. In a study conducted among European men, Mackenbach et al. [3] found that 20% of the educational differences in those who suffered premature mortality were attributable to smoking. Extensive international literature offers evidence that tobacco does not affect all socioeconomic subgroups of the population equally (it is estimated that smoking prevalence is about 50% higher in lower socioeconomic groups than in higher groups [4]). Giskes et al. [5] analysed trends in smoking behaviour by education level between 1985 and 2000 in Western Europe. They found a greater decline in smoking prevalence and consumption levels among more educated individuals. Huisman et al. [6] also found that education was a strong predictor of smoking in Europe. In a study among British women, Harman et al. [7] identified socioeconomic gradients for ever-smoking, quitting and current smoking. Using six socioeconomic indicators, Laaksonen et al. [8] identified a strong association between education, occupational status and current smoking. Cavelaars et al. [9] found higher rates of current and ever-smoking among less educated individuals in northern European countries. Barbeau et al. [10] found the same type of association in the United States, where they noted an increased prevalence of current smoking and an independent association between current smoking and lower-paid jobs, low education levels and lower income levels. Moreover, they found a positive association between success in quitting and socioeconomic resources. This last finding is supported by the studies of Borland et al. [11], and more recently Lee and Kahende [12], in which the authors found an association between certain socioeconomic indicators and the probability of successfully quitting. In a recent review, Schaap and Kunst [13] noticed that the majority of studies on socioeconomic inequalities in smoking focused on education and used smoking prevalence as the outcome of interest. The authors emphasized the importance of analysing smoking inequalities with respect to other socioeconomic indicators and various smoking outcomes related to initiation and cessation. With this in mind, we decided to analyse the association between two socioeconomic indicators—education and income—and two outcomes related to smoking cessation: the odds of successfully quitting and the duration of abstinence. In a first step, we conducted multivariate logistic regressions to assess the socioeconomic differences between successful and unsuccessful quitters. Then, relying on detailed information about past smoking behaviour, we retrieved the abstinence episodes of both successful and unsuccessful quitters. The resulting information on time before relapse was analysed in the duration analysis framework. To our knowledge, ours is the first study to assess the simultaneous impact of several socioeconomic indicators on abstinence duration. This approach allowed us to conduct a comprehensive analysis of smoking cessation, relying on a more detailed temporal dimension. For both parts of the study we used pooled data from the 2001–2007 editions of the Swiss Tobacco Survey [14]. In each case, we controlled for potential confounders such as age, region, and other health-related