The current study examined mother-grandmother interactions related to emotional socialization in response to the negative emotional references of the eldest son A and the eldest daughter B (who are in the upper grades of primary school), based on observations of dinnertime conversations over a 7-month period among three generations, including a set of three school-aged siblings. The mother’s and grandmother’s emotional socialization responses were focused on (1) emotion suppression and regulation, (2) appropriate expression of emotions, and (3) understanding of their own and others’ emotions. As a result, many of the responses related to “cause modification” in (2) were common to both mothers and grandmothers across all topics. In addition, the mothers’ and grandmothers’ responses had complete or partial agreement on 69.0% of the topics at the category level of (1) to (3). These topics indicated that the mothers and grandmothers were collaborating and focusing on responses considered important in socialization based on a shared perspective. In these exchanges, the mother’s additional responses to the grandmother’s references (Topic 1), the grandmother’s and mother’s persuasive responses to each other’s references (Topic 4), and the mother’s agreement with the grandmother (Topic 2) were also observed. Moreover, the topic where the mother and grandmother‘s responses did not agree (Topic 5) indicated that the mother and grandmother expanded their perspectives and interpretations of the event based on their respective points of view regarding a single topic. Furthermore, analysis of these interactions indicated that the grandmother’s words, actions, and presence may have played a role in the interaction between mother and child and in reducing emotional conflicts between the siblings. Overall, results suggested that conversations about negative emotional references among three generations, including grandmothers, play an important role in the development of emotional competence through emotional socialization.