European bi-national marriages as a special case of interethnic unions have received relatively little attention in research. Existing studies on interethnic marriage mainly orient on union formation among non-western migrants and in particular intermarriages between the majority group and non-western migrants, which are often perceived as indicators for integration. European intermarriages can nonetheless be of similar interest from the perspective of European integration and identity formation. In this article, we first study the patterns and trends in bi-national European marriages in Belgium. Second, we analyse the diversity in bi-nationally married couples, and third, we pinpoint the characteristics of these European couples. We use the Belgian marriage register data from 1989 to 2010 as well as the census data from 2001. Our findings show that European bi-national marriages are still relatively limited in Belgium and that their numbers (and proportion) have remained constant over time over the past decade. There is nevertheless variety in the level of intermarriage among different nationality groups. Our analyses point to six different types of European bi-national marriages with different characteristics of the partners and their place of residence. keywords: intermarriage; European mobility; European integration; bi-national marriages; free movers ; European bi-national marriages as a special case of interethnic unions have received relatively little attention in research. Existing studies on interethnic marriage mainly orient on union formation among non-western migrants and in particular intermarriages between the majority group and non-western migrants, which are often perceived as indicators for integration. European intermarriages can nonetheless be of similar interest from the perspective of European integration and identity formation. In this article, we first study the patterns and trends in bi-national European marriages in Belgium. Second, we analyse the diversity in bi-nationally married ...