The aim of this PhD thesis was to carefully describe trends in old-age mortality in seven European low-mortality countries from 1950 to 1999, and to assess the role of specific factors in explaining the observed trends. For this purpose, we studied both all-cause mortality and mortality from 26 specific causes of death, we applied a life-course perspective – with emphasis on both immediate effects of circumstances prevailing at old age (= period effects) and possible long-lasting effects of determinants located earlier in life (=cohort effects) – and we performed comparative studies among seven countries, i.e. Denmark, England and Wales, Finland, France, the Netherlands, Norway, and Sweden. In a series of separate analyses, we assessed the role of smoking, mortality selection, socio-economic developments over the life-course, and medical end-of-life decision-making.