Résumé : This article explores Russia's impact upon the cohesion of the European Union International Society (EUIS). The analysis proceeds from a systematic categorisation of Member States' positions towards Russia, using an "index of friendliness towards Russia" based on various indicators. This index allows us to analyse the relative positions of Member States towards the Eastern neighbour and to order them along an ideal continuum which goes from "normative adamant" to "normative docile". By taking a broad perspective of the different national attitudes, this article offers an innovative approach to the key question of EU-Russian relations. Existing cleavages and social differences among the members bear an important divisive effect on the development of the EUIS. The present analysis explores adherence to norms deriving from the widely accepted institutions of sovereignty and the market. While there is no doubt that these institutions boast complete devotion on behalf of EU Member States (MSs), translation into both common language and action proves to be hindered by social differences among members. The difference among the preferences of Member States towards Russia is then compared to the preferences expressed by the Members of the European Parliament (MEPs) during the 6th legislature. The analysis of MEPs' voting behaviours towards Russia explores whether there is a coincidence between the positions of the MSs and those of the MEPs, as representatives of the EU's societies.