We examine the effects of fertility on men’s international migration in Nepal, a setting in which fertility and son preference remain prevalent and migration for work is increasingly common. We analyze how (1) the transition to fatherhood and, among fathers, children’s characteristics––(2) age and (3) gender––influence 1,381 men’s subsequent risk of international migration (N=93,102 person-months). Findings from fixed effects logistic regression models show that fatherhood is a powerful predictor of migration, although the odds vary by children’s characteristics: having children of primary and secondary school-age significantly increases men’s migration, particularly when the children are sons. Additional analyses show that achieving, or going beyond, ideal fertility increases the odds of international migration among men without a son preference, regardless of the sex composition of their children, whereas having sons positively predicts migration among those with son preference, regardless of the number of children they have compared to their stated ideal.