Since the mid-nineteen century life expectancy in developed countries has doubled, increasing from levels around 40 years to above 80 years. This research project is motivated by the need to further explore how societies have achieved the current levels of longevity, in terms of life expectancy and modal age at death. To achieve this, age-patterns and time-trends in cause of death contribution to longevity are assessed. This historical analysis is carried out in fifty developed and developing countries/areas. It is expected that the cause of death contribution to the advancement of longevity is country/region specific. However, the hypothesis to be tested is that there are common cause-specific time-trends across countries which can be described by a model of cause of death contribution to longevity. Several purposes for such a model can be listed: it will allow us to study expected future mortality directions in developed nations that are currently still facing high levels of some particular causes of death, e.g. the Netherlands and United States. It could also help investigating the retrocession in mortality observed in some transitional countries/areas, particularly in Eastern Europe. Finally, the accelerated epidemiological transition in developing countries is compared to the slower trend in the developed world at earlier times, model results versus observed cause-contribution. The interest in the latter comparison is to foresee the increase in the prevalence of chronic disease in low-income countries predicted by the WHO and the World Bank. Furthermore, one in every three countries in the world has adequate cause-specific mortality data. The proposed model could facilitate estimating the current cause of death status in developing countries. This project addresses a significant question concerning the mechanisms (age and cause of death) that direct reductions in mortality.