Pré-publication, Document de travail: We study the design of a fair family policy in an economy where parent- hood is regarded either as desirable or as undesirable, and where there is imperfect fertility control, leading to involuntary childlessness/parenthood. Using an equivalent consumption approach in the consumption-fertility space, we .rst show that the identi.cation of the worst-o¤ individuals is not robust to how the social evaluator .xes the reference fertility level. Adopting the ex post egalitarian social criterion, which gives priority to the worst o¤ in realized terms, we then examine the compensation for involuntary childlessness/parenthood. Unlike real-world family policies, a fair family policy does not always involve positive family allowances to (voluntary) parents, and may also, under some reference fertility lev- els, involve positive childlessness allowances. Our results are robust to assuming asymmetric information and to introducing Assisted Reproduc- tive Technologies.