A semi-structured observational study investigated gender differences in delivered and received relational, physical, verbal, and nonverbal aggression in a young preschool sample (N=60). Findings revealed that gender differences in subtypes of aggression may be apparent as early as 3 years of age. Specifically, girls were found to deliver and receive more relational aggression than males, whereas boys tended, although not significantly, to deliver and significantly received more physical aggression than females. Relational and physical subtypes of delivered and received aggression were differentially associated with preschoolers' social-psychological adjustment.