Many studies have attempted to understand observed social variations in cardiovascular disease in terms of sets of intermediate or confounding risk factors. Tests of these models have tended to produce inconsistent evidence. This paper examines the relationships to cardiovascular risk factors or two theoretically based measures of social position. It shows that the strength of the relationships between social position and cardiovascular risk factors varies according to the definition of social position which is used: there is a closer relationship between most health behaviours and the Cambridge scale, an indicator of 'general social advantage and lifestyle', whereas the Erikson-Goldthorpe schema, which is based on employment relations and conditions, is more strongly related to work control and breathlessness. The implications of these findings for understanding the conflicting evidence in other studies of health inequalities are then discussed. The paper concludes that inconsistencies between studies may be in part due to unexamined differences between the conceptual bases of the measures of social position they use, combined with a failure to make explicit the hypothetical mechanisms of effect. If neither the conceptual basis of the measure of social position, nor the links between social position and health outcome tested in each study are clear, inconsistencies between studies will be difficult to interpret, making policy recommendations highly problematic.