This paper claims that the protection of children's capability for play is a central socialpolitical goal. It provides the following three-premise argument in defence of this claim: (i) we have strong and wide-ranging normative reasons to be concerned with clusters of social deficiency; (ii) particular fertile functionings play a key role for tackling clusters of social deficiency; and finally (iii) the capability for childhood play is a crucial, ontogenetic prerequisite for the development of those particular fertile functionings. Thus, in so far as we consider it a central political goal to tackle social deficiency, we should be concerned with protection of childhood play capability. This conclusion raises new insights on the importance-for global development policy as well as for welfare states' aim to secure social justice-of protecting children's capability to engage in playful activities.