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. (PsycINFO Database Record (c) 2019 APA, all rights reserved).