To investigate children's ability to describe and make inferences about feelings, thoughts, and intentions that occur in interpersonal relationships, 60 middle class girls were divided into three age groups: 6, 9, and 12 years. Each group viewed two sections of a movie portraying episodes of social interaction. After each section, the children gave an account of the episodes in their own words and then answered specific questions. Developmental trends of descriptions appeared in the children's accounts. Wherever there were statistical differences between 6- and 12-year-olds, there were statistical differences between 6- and 9-year-olds. Older children gave more causal explanations. Between ages 6 and 9, shifts occurred in the kinds of explanations offered and inferences of feelings made. When responses to specific questions were scored on a three-point scale of complexity, developmental trends occurred in responses explaining behavior and naming feelings. A content analysis of the children's accounts and responses to specific questions revealed that 6-year-olds tended to mention actions and describe scenes, whereas the older groups reported adult communications and feelings and were better able to answer specific questions on adult motivations. The study suggested that an important transitional phase in understanding social interaction occurs between the ages of 6 and 9. (JS)