The present study explored sex differences in children's expression and control of fantasy and overt aggression. Fifth-grade boys and girls were presented a TAT-like projective test to measure fantasy aggression and controls over aggression. Overt peer-oriented aggression was measured by peer and teacher ratings. Results indicated that boys were rated more physically and verbally aggressive than girls but not more indirectly aggressive. Boys also produced more physical aggression in fantasy than girls, although the opposite trend was found for indirect aggression; no sex difference was found for verbal fantasy aggression. Finally, girls had a higher ratio of aggression control per total fantasy aggression than boys. The results support the position that while boys, in contrast to girls, are socialized in a way that encourage direct expression of aggression, girls are just as likely to be aggressive as boys when the aggression is indirect. The results are discussed further from the perspective of social learning theory and Maccoby and Jacklin's biological position.