The estimation of health risks is central to preventive medicine and health policies. On the basis of epidemiological studies risk factors and high risk populations are identified, models of risk calculation are developed and risk assessment tools are tested. In this production of risk knowledge (as well as in its application) individual and population are entangled in specific ways: On the one hand (bio-)information of individuals is stored in databanks and is made usable in epidemiological research in order to develop statistical models; on the other hand this population-based risk knowledge is individualized in quantified estimates of future disease risks (Holmberg et al. 2012, Holmberg/Parascandola 2010). As interfaces between research and society such individualized risk calculations present an interesting case for the discussion of the quantification of health and illness. In which situations are risk estimates used by whom? How are they transformed and negotiated in these different contexts and usages? And what are the social and political consequences of such quantified practices of measuring health? In order to discuss these questions the paper presents results of an enquiry in preparation of an ethnographic investigation of epidemiological risk scores. Taking one (to two) risk score(s) as an example the 'social life' and circulation of quantified/individualized risk knowledge will be mapped and analyzed.