Fertility decisions typically involve two persons. This raises the question of how individual desires for further children transform into joint proceptive or contraceptive behavior. Previous research has proposed different approaches to this question, emphasizing either gender, joint utility, consensus, or bargaining power as key elements. We use data from the German Family Panel (PAIRFAM) to test competing hypotheses derived from existing models. We find that men and women have equal influence on the joint decision, given the strength of their child preferences. Besides this general result confirming models of joint utility there is also some evidence that men or women with a strong preference against further children exert a certain veto power on their partners, whereas only women’s bargaining power plays a role in getting their will against their partner’s desires.