This study investigates the determinants of female underemployment in Australia. The presence of offspring reduces the likelihood of underemployment, especially for part-time employed females, suggestive of mothers taking the burden of domestic duties, thus voluntarily reducing their working hours. Age of offspring matters: younger (older) offspring reduces (increases) the likelihood of underemployment. This impact is generally, but not wholly, accentuated for casual workers. Relevant labour market policies should have a gender lens that better accounts for the heterogeneity in characteristics of the female labour force. Better integration between the labour market and childcare would be a valuable starting point to address the issue of female underemployment.