This talk is based on a unique, new project that aims at bringing to light the late anthropologist Arthur P. Wolf’s unpublished research on children and childrearing in a village near Taipei, Taiwan, conducted in 1958 – 1960. Designed as an improved replication of the Six Cultures Study, a landmark project in the anthropology of children and childhood, Wolf’s work was the first anthropological and mixed-methods research on ethnic Han children. Drawing from standardized interviews with 79 children (ages 3-10) as well as around 2000 systematic observations of children’s interactions, this talk focuses on peer aggression scenarios. I approach these materials from a cognitive anthropology theoretical framework and combine ethnographic analysis with statistical as well as text-mining methods. Children’s narratives reveal a complex spectrum of reciprocity in their own understandings about peer aggression, their perceptions and reactions reflecting important concerns and strategies in local socio-moral life. Together with observational texts, children’s world of peer aggression poses a stark contrast to parenting ideologies and adult moral norms. Taken together, these findings add an important theme, “negative reciprocity”--defined as responding to a negative action with a negative action, to the recent advocacy in anthropology for taking children seriously in understanding human morality. Moreover, these peer aggression narratives and observations illuminate a dark side of moral development that would otherwise remain obscured in literature of Chinese childhood, therefore my study contributes to bridging anthropological and historical studies of childhood.