Cross-national comparisons form the basis of much of what we understand about the link between gender inequality at the societal level and family change. There has been little attention to this process in the United States, despite substantial variation in structural features of gender inequality and families across states. We leverage this variation to examine how state-level gender inequality shapes couple-level inequality following the critical transition to parenthood, in particular how state gender wage gaps, parenthood employment penalties, early family formation, and attitudes about working mothers moderate changes in couples’ relative earnings after a first birth. Our study relies on newly available identifiers in the Current Population Survey to link couples longitudinally across the 16 months of their participation in the survey, and it includes four decades of overlapping panels. Preliminary findings suggest that state-level gender inequality shapes couples’ responses to birth, with greater within-household inequality in earnings among couples living in states with fewer working mothers and less progressive attitudes about working mothers.