Ethnic diversity has been posed as a threat to social capital, but results from existing research are inconclusive. This study takes as its starting point that different aspects of social capital may be influenced differently by ethnic diversity and uses one specific welfare state context – Norway – to explore such variations. Analysing an original dataset, nine different measures are used to explore three dimensions of social capital in 61 communities in Norway, amongst the majority population and residents with immigrant background. The results suggest, first, a differentiated impact of ethnic heterogeneity on trust. Ethnic diversity is negatively associated with spatially bounded forms of trust, but not with generalized trust. Second, a negative association with traditional forms of voluntarism is found – albeit this latter relationship is much weaker than the former. Third, the results suggest that these relationships are fairly similar across different (immigrant) groups. Although residents with immigrant background typically express lower levels of generalized trust than the majority population, the relative differences between residents living in diverse or homogeneous communities are limited. Given its strong institutions Norway could be seen as a least likely case for studying the impact of ethnic diversity on social capital. On the one hand, effects are more limited than what has been found in studies from the United States. On the other hand, the fact that effects are found on community trust and volunteering indicates that this type of societal model can indeed be affected by ethnic diversification.