Sex differences in antisocial behavior in 20 elementary school children were explored by using two constructs: need for achievement and need for social approval. It was hypothesized that sex differences would appear only under certain conditions. For boys, more antisocial behavior would occur when the need for achievement was frustrated, while for girls, frustration of the need for social approval would produce more antisocial behavior. Results were interpreted in terms of sex stereotypes and their subsequent effects on boys and on girls. (SBT)