The purpose of the present study was to explore the detection of prosocial lying in children. Six‐ to 11‐year‐olds and adults were videotaped telling the truth or a lie about the desirability of an object, sometimes being asked a follow‐up question (i.e., elaborative trials) and other times not (i.e., regular trials). A different group of adults and children then judged the veracity of the individuals' statements in the video clips. Adults and children performed significantly better than chance at detecting lies in the youngest age group, and children's detection performance was unrelated to their age. Child lie detectors, unlike the adults, were also able to discriminate between adults' truthful and untruthful statements in the regular trials, but misidentified adults' truthful responses as lies. They appeared to be more trusting of other children. Copyright © 2016 John Wiley & Sons, Ltd.