Studies on fertility among second-generation migrant women across Europe have mainly treated the second generation as a rather homogenous group, not linking and distinguishing fertility patterns by type of partner. This study investigates how and to what extent the origin and generation of the partner (endogamous or exogamous as well as diversity in endogamy) of Turkish and Moroccan second-generation women in Belgium is related to first-birth rates. We distinguish three types of partnerships: those in an endogamous union with a first-generation partner, those in an endogamous union with a second-generation partner, and those in an exogenous union where the partner is of native Belgian origin. We use linked Census-Register data for the perio...