[영문]This article presents an analysis of trends in mortality differentials and life expectancy by average relative earnings for male Social Security -- covered workers aged 60 or older. For this study, time trends are examined by observing how mortality differentials by average relative earnings have been changing over 29 years of successive birth cohorts that encompass roughly the first third of the 20th century. This study finds a difference in both the level and the rate of change in mortality improvement over time by socioeconomic status for male Social Security -- covered workers. The life expectancy estimates in this article represent one possible outcome under one set of assumptions. These projections should not be regarded as an accurate depiction of the future. Specifically, this study adopts a simple projection method in which differentials are assumed to follow the pattern observed over the last 30 years of the 20th century for the first 30 years of the 21st century.