The main purpose of this research is to investigate social capital and its determinants in three South-East European countries (namely, Bosnia and Herzegovina, Serbia and Croatia) focusing its attention on different migrant groups and different periods (crisis and normality). The project examines a post-conflict environment of SEE region and factors which influence social-capital in the areas where social capital is likely to have an important role in the re-integration, and indirectly, in supporting economic performance of individuals, companies and the whole societies. In the context of policy relevance, this research identifies common and specific determinants of social capital as well as similarities and differences for the periods of crisis and normality. A particular focus is devoted to the effect of ethnic diversity on social capital and later on economic performance of individuals and families. The authors find that the current ethnic diversity of neighbouring areas and personal networks is beneficial for both, pro-social engagement of citizens as well as for individual and household economic performance. This finding provide an important policy implication for the societies that are straggling with number of inter-ethnic challenges with a massage that ethnic diversity is not a treat but benefit for such societies, families and individuals living in them.