Children tell prosocial lies from the age of three years onward, but little is known about for whom they are inclined to lie. This preregistered study examined children's (N = 138, 9-12 years) prosocial lying behavior toward minimal in-group and out-group peers. Additionally, children evaluated vignettes in which an in-group peer told a prosocial lie to an in-group or out-group peer. Results show that only older children told more prosocial lies for the benefit of in-group compared with out-group peers. Further, in the vignettes children of all ages were more accepting of prosocial lying in favor of in-group members compared with out-group members. These findings underscore the importance of considering intergroup relations in children's prosocial lying behavior and advocate for broadening the scope of research on children's intergroup prosociality.