Over the last two decades there has been an exponential increase in the number of publications that have examined the association between socioeconomic position (SEP) and a wide variety of health outcomes examined the association between socioeconomic position (SEP) and a wide variety of health outcomes. For example, according to a MEDLINE search, well over 700 articles on the association between income and mortality have appeared since 1990, not including analyses that only included income as an adjustment variable. For most outcomes, a graded inverse association has been found, with higher SEP associated with lower risk of these outcomes. While some recent attention has turned to estimating the contribution of reverse selection (poor health leading to low income) to these observed associations, there are additional critical issues that are necessary to resolve, the answers to which will also have some bearing upon the argument over the causal effect of income on health. We propose to examine whether or not the benefits of increasing income on risk of death are primarily felt at lower incomes, if the protective effects of income decrease with increasing income- whether there are important non-linearities in this "gradient," and calculate the relative concentration of deaths in different parts of the income distribution. In addition we will add to the literature by considering the differential contribution of taxes and transfers to the association between income and mortality and their impact on the concentration of mortality, analyses not previously done. Using three large longitudinal studies, representative of the US population, the proposed study will estimate the shape of the association between income and risk of death from all causes and common causes, where the greatest burden of mortality falls in the income distribution, and analyze the extent to which tax and transfer programs alter the shape of this association. In addition, it will coordinate efforts of an experienced set of researchers conducting identical analyses in Canada, Denmark, Finland, Norway, and Sweden in order to examine in a broader context the nature of the association between income and mortality risk, and to explore the role of tax and transfer policies in the income-mortality association. By bringing together investigators conducting identical analyses in countries that differ with regard to their commitment to social welfare policies we hope to inform the discussion of the health benefits of such policies. PUBLIC HEALTH RELEVANCE: The proposed exploratory study contributes to our understanding of socioeconomic inequalities in mortality by carefully estimating the exact shape of this relationship between income and mortality, where the burden of income-related mortality falls in the population, and whether or not tax and transfer programs have an impact on mortality in the population. In addition, by coordinating a set of identical analyses in five other countries (Canada, Denmark, Finland, Norway, Sweden) we hope to gain some insight into the possible impact of more redistributive tax and transfer policies on the distribution of the mortality burden in the population.