This book provides an overview of recent research presenting conflicting interpretations of children's understanding of the psychology of pretense and describes sociocultural factors which influence children's pretenses. Studies of nonhuman primates provide examples of their pretenses and other simulative activities, explore their representational and imaginative capacities and compare their skills with children. Although the psychological requirements for pretending are controversial, evidence presented in this volume suggests that great apes and even monkeys may share capacities for imagination with children and that children's early pretenses may be less psychological than they appear.