It is argued that although the importance of party identification and social cleavages is declining, the bipolarity of the Swedish party system is sustained by voters' identification with political blocs rather than with parties. Using data from the Swedish election of 2010, the article shows that voters' bloc identification structures their voting behaviour and stabilises the party system. Four hypotheses are tested and supported. H1: Declining party identification has been replaced by bloc identification. H2: Voters with a strong bloc identification are often detached from a strong party identification, while almost all of the few voters with a strong party identification are also attached to a strong bloc identification. H3: Bloc identification has an effect on voting for parties belonging to one of the political blocs, even when party identification is controlled for. H4: Bloc identification has a small effect on electoral support for anti-establishment parties (such as the Sweden Democrats).