A spate of recent work has demonstrated tensions between ethno-cultural diversity levels and social capital (Putnam, 2007; Hooghe et al., 2007). In “E Pluribus Unum”, Putnam has indicated that societies premised on a civic understanding of nationhood are better able to overcome the negative consequences of diversity (2007). In this respect, Putnam follows the logic of David Miller (1995, 2000), who for more than ten years underscores the positive elements of nationalism as being able to craft cross-group trust and other aspects of horizontal solidarity among fellow countrymen. In this paper, we will submit two theoretical hypotheses to an empirical test. On the one hand, according to the Miller-thesis, a strong sense of attachment to the nation can foster generalized trust, particularly if the national self-definition is ‘civic’ in character rather than ‘ethnic’. On the second hand hand, along similar lines, the Putnam-thesis states that ‘civic’ nations are less likely to suffer reduced social capital in response to increased diversity. We test these hypotheses on 27 countries using both contextual-level data and the latest wave of the European Values Study (2008). Though the evidence is mixed on ‘civic’ nationalism, we find strong evidence that ethnic nationalism goes hand-in-hand with reduced social capital, and that it increases the negative social impact of diversity. So, while our study only partially confirms the benefits of ‘civic’ nationalism, it clearly underlines the costs of its ‘ethnic’ variety.
