During the last century, Kerala witnessed drastic mortality reduction and high improvement in longevity. This achievement is often compared with that of developed countries. However, how far the early advantages in mortality reduction have further enhanced in Kerala remains unknown. In most developed countries, advanced stage of mortality reduction and further increase in longevity was achieved mainly due to the mortality shift from adult and older ages to oldest ages (Olshansky and Ault 1986). Considering the lack of comprehensive study on the change in longevity in Kerala, this study focuses on discovering (i) the historical time-periods that provided the biggest gain to life expectancy and also the beneficiaries (by age group and sex) and (ii) the contributions of major groups of causes of death in mortality reduction and consequent improvement in longevity. The study uses the methodology proposed by Olshansky and Ault in 1986. It used methods such as Temporary Life Expectancy (TLE), Annual Relative Change in TLE, Decomposition of changes in longevity among different age groups (gender and spatial) and causes of deaths, for the analysis. It used data from various sources such as Census, Civil Registration System (CRS) and Directorate of Health Services (DHS), as well as survey data from Sample Registration System (SRS) and Medically Certified Causes of Deaths (MCCD) for this study. The study found that overall mortality dramatically declined in the state in the recent decades. Younger ages have contributed the most for this reduction. Therefore, further mortality reduction is possible in adult and early old ages. However, the contribution of these ages to life expectancy was lower than that of youngsters until 1991-2000 especially among males. This may indicate a slow progress towards the advanced stage of epidemiological transition characterized by high prevalence of non-communicable diseases. The paper concludes that although the health issues of infants, children, and mothers in the reproductive age group, are effectively addressed through various policies in Kerala, the state needs to focus more on the health problems of adults, especially males.