ABSTRACT My primary aim is to call into question an influential notion of paternal responsibility, namely, that fathers owe support to their children due to their causal responsibility for their existence. I argue that men who impregnate women unintentionally, and despite having taken preventative measures, do not owe child support to their children as a matter of justice; their children have no right against them for support. I argue for this on the basis of plausible principles of responsibility which have been used to defend abortion rights. I then consider the morally relevant differences between men and women, arguing that while in some cases these differences may justify differential treatment, their import should not be overstated — in many cases, the burden of child support will be too great to impose justly on fathers. This conclusion is not as undesirable as it may seem: I suggest feminist considerations in favour of revising the notion of paternal responsibility and consider alternative arrangements of child support.