This paper examines the relationship between children's theoretical knowledge of wild food plants in relation to sociocultural group, sex, and age in the context of social and environmental change. Theoretical knowledge was assessed by evaluating the composition of the cultural domain of “wild food plants,” naming ability, and cognitive salience. Freelistings were conducted with 57 Indigenous Shipibo-Konibo children and 57 mestizo children in Ucayali, one of the regions with the highest deforestation rates in the Peruvian Amazon. A total of 120 plants were listed by all children, with 72 listed by Indigenous and 95 by mestizo children. Most species listed as wild food plants have been classified as domesticated species by scientists. The main factor affecting variation in children's theoretical knowledge was sociocultural group. Mestizo children included more introduced crops in their lists, whereas, for Indigenous children, the most salient species were those that required specific abilities or knowledge to be consumed. Older children presented statistically significant longer lists than younger children, but there were no statistical differences in list length in relation to sex. We conclude by discussing the definition of “wild” versus domesticated plants and the effect of socioecological change on children's ethnobotanical knowledge as the landscape transforms in the forest-agriculture interface.