The aim of the present study was to explore how maternal reminiscing relates to socioemotional development during middle childhood. Specifically, analyses explored the link between maternal reminiscing and children's internalizing (emotional problems and peer problems), externalizing (hyperactivity and conduct problems) and prosocial behavior within a large and diverse sample of New Zealand families, after controlling for a range of child and maternal sociodemographic factors. A subset of 1404 mother-child dyads (663 boys) were selected from the longitudinal study "Growing Up in New Zealand's" 8-year data collection wave. Mother-child reminiscing conversations about a past negative emotional event were coded using a scale-based measure of maternal elaboration. After controlling for child and maternal sociodemographic characteristics, regression analyses identified unique associations between maternal reminiscing style and children's concurrent scores on the Strengths and Difficulties Questionnaire. Overall, greater maternal elaboration was associated with fewer child emotional problems and greater child prosocial behavior. This study presents novel data exploring the importance of mother-child reminiscing interactions at a critical and sensitive time in child development. Future research should explore bidirectional influences across time between mothers' elaborative reminiscing and children's socioemotional development.