The contribution of children's social environment to their acquisition of theory of mind skills, combined with the well documented advantage for girls in mental state talk with siblings, peers and mothers, might lead to a female advantage on false belief tasks. We present a post-hoc analysis of large datasets from two independent laboratories. A slight advantage for girls on false belief task performance was found in both datasets and was only apparent in younger but not older children. Language ability could be controlled for only in a smaller subsample of one dataset and cannot be ruled out as a potential mediator of this effect. However, if there is an age-specific advantage for girls in false belief acquisition it is a weak effect only.