We document that female breadwinners do more home production than their male partners, driven by “housework” like cooking and cleaning. By comparing to same sex couples, we highlight that specialization within heterosexual households does not appear to be “gender neutral” even after accounting for average earnings differences. One possible explanation would be a large comparative advantage in housework by women, a supposition commonly used to match aggregate labor supply statistics. Using a model, we show that while comparative advantage can match some stylized facts about how couples divide housework, it fails to match others, particularly that men’s housework time is inelastic to relative household wages. Matching these facts requires some gendered wedge between the opportunity cost of housework time and its assignment within the household. We then turn to the implications for household formation. Gendered rigidities in the allocation of household tasks result in lower surplus for couples where women out-earn men than vice versa, providing a micro-founded reason for substantial literature showing that lower relative earning by men decreases marriage rates. We show that our mechanism—allocation of housework, rather than norms about earnings—plays a role by relating marriage rates to the ratio of home production time in US immigrants’ countries of origin.