Background: Adult lifespan variation has been stagnant since the 1960s in most developed countries, despite increases in longevity. However, national averages mask large socioeconomic differences. In Finland lifespan variation among the highest occupational class has continued to decline, while the lower classes have experienced stagnation. Objective: We aimed to investigate the role that smoking has played in the occupational social class divergence in lifespan variation since the 1970s. Methods: Finnish register data (1971-2010) by occupational social class, ages 50+, was used. Smoking-attributable mortality was estimated by the Preston, Glei, and Wilmoth (2010) method. Results: We expected smoking-attributable mortality to explain the divergence by occupational class because smoking is socially patterned and particularly important for middle- and young-old-age mortality, ages which contribute greatly to lifespan variation. Instead, we found that among men social class differences would have widened even further without smoking; for women lifespan variation was unaffected by smoking. Conclusions: The maturation of the smoking epidemic will not decrease uncertainty in the timing of death or reduce inequalities in this dimension of mortality by occupational class in Finland.