BACKGROUND: Many important social determinants of health are also the focus for social policies. Welfare states contribute to the resources available for their citizens through cash transfer programmes and subsidised services. Although all rich nations have welfare programmes, there are clear cross-national differences with respect to their design and generosity. These differences are evident in national variations in poverty rates, especially among children and elderly people. We investigated to what extent variations in family and pension policies are linked to infant mortality and old-age excess mortality. METHODS: Infant mortality rates and old-age excess mortality rates were analysed in relation to social policy characteristics and generosity. We did pooled cross-sectional time-series analyses of 18 OECD (Organisation for Economic Co-operation and Development) countries during the period 1970-2000 for family policies and 1950-2000 for pension policies. FINDINGS: Increased generosity in family policies that support dual-earner families is linked with lower infant mortality rates, whereas the generosity in family policies that support more traditional families with gainfully employed men and homemaking women is not. An increase by one percentage point in dual-earner support lowers infant mortality by 0.04 deaths per 1000 births. Generosity in basic security type of pensions is linked to lower old-age excess mortality, whereas the generosity of earnings-related income security pensions is not. An increase by one percentage point in basic security pensions is associated with a decrease in the old age excess mortality by 0.02 for men as well as for women. INTERPRETATION: The ways in which social policies are designed, as well as their generosity, are important for health because of the increase in resources that social policies entail. Hence, social policies are of major importance for how we can tackle the social determinants of health.