Using 2000 U.S. Census data we illustrate the importance of accounting for household specialization in lesbian couples when examining labor supply differences between heterosexual married and partnered lesbian women. Specifically, we find the labor supply gap is substantially larger between married women and partnered lesbian women who specialize in market production (primary earners) than between married women and partnered lesbian women who specialize in household production (secondary earners). Applying a semi-parametric decomposition approach we show that controlling for children significantly reduces the gap between married women and secondary lesbian earners both in terms of the decision to remain attached to the labor market (the extensive margin) and annual hours of work conditional on working (the intensive margin). Further, the effect of controlling for children primarily reduces the percentage of secondary lesbian earners working extremely high annual hours
