This study investigates how married mothers’ relative bargaining power before the birth of their first child affects their subsequent accumulation of pension entitlements in East versus West Germany. I use a novel data linkage between the German sample of the “Survey of Health, Ageing and Retirement in Europe” and administrative records from the German pension insurance (SHARE-RV) to analyze monthly life-course data on married mothers from East (N = 226) and West Germany (N = 586) who were born between 1925 and 1967. Applying random effects growth curve models and mediation analyses, I find that women’s relative bargaining power before parenthood is linked to their subsequent accumulation of pension entitlements in West (but not East) Germany. The results support the notion that bargaining power early in couples’ linked lives has long-term consequences for women’s pension income. Moreover, the results indicate that negotiations within the couple are constricted by the extent to which the institutional context supports or hinders the reconciliation of women’s work–family conflict.