In this paper we make use of data from the official statistics to analyze transnational marriage among immigrants in Germany. Pooling all currently available Scientific Use Files of the German Microcensus between 1976 and 2004, we are able to contribute empirical findings that are unique in their scope and their degree of differentiation. We look at the five most common groups of former labour migrants and study group-specific trends over generations and time. Our empirical analysis is guided by four basic expectations, which are anchored in a more general theoretical framework of immigrants’ marriage behaviour. We find, as expected, large group differences in the propensity to select a spouse from one’s own country of origin. Assumed effects of the opportunity structure, however, can only be confirmed for women. Central derivations from a general assimilationist view are also only partly supported: A general increase in transnational marriages among ex-Yugoslav and Turkish women over marriage cohorts, and the absence of any effects of structural assimilation on the propensity toward transnational marriages are the most puzzling results.