Relations between an early interest in violent fantasy and children's social understanding, antisocial and emotional behavior, and interactions with friends were investigated in 40 “hard-to-manage” preschoolers and 40 control children matched for gender, age, and school and ethnic background. Children were filmed alone in a room with a friend, and tested on a battery of cognitive tests, including false-belief, executive function, and emotion understanding tasks. Teachers reported on their friendship quality. At age 6 years, the children's understanding of the emotional consequences of antisocial and prosocial actions was studied. The hard-to-manage group showed higher rates of violent fantasy; across both groups combined, violent fantasy was related to poor executive control and language ability, frequent antisocial behavior, displays of anger and refusal to help a friend, poor communication and coordination of play, more conflict with a friend, and less empathic moral sensibility 2 years later. The usefulness of a focus on the content of children's pretend play — in particular, violent fantasy — as a window on children's preoccupations is considered.