Pré-publication, Document de travail: Although the optimal policy under endogenous fertility has been widely studied, the optimal public intervention under endogenous childbearing age has remained largely unexplored. This paper examines the optimal family policy in a context where the number and the timing of births are chosen by individuals who differ as to how early fertility can weaken future earnings growth. We analyze the design of a policy of family allowances and of public pensions in such a setting, under distinct informational environments. We show how endogenous childbearing ages affect the optimalpolicy, through the redistribution across the earnings dimension and the internalization of fertility externalities. It is also shown that, contrary to common practice, children benefits differentiated according to the age of parents can, under some conditions, be part of the optimal family policy.