The way that mothers talk about the past (reminisce) with young children is linked to key memory, language, and socioemotional outcomes. The present research explored the role of a range of child, maternal, socioeconomic, and cultural factors that predict maternal reminiscing style, with a particular focus on maternal personality and child temperament. A total of 1,404 mother-child dyads from the prebirth longitudinal cohort study "Growing Up in New Zealand" (https://www.growingup.co.nz) participated in a reminiscing task about a negative event when children were 8 years old. This broader cohort is broadly representative of the New Zealand population in terms of maternal ethnicity and socioeconomic status. Conversations were scored using a revised version of the Elaborative Reminiscing Scale. Child temperament during infancy, but not childhood, uniquely predicted maternal reminiscing style. Maternal extraversion also predicted a more elaborative reminiscing style. Other maternal factors, including education, ethnicity, and age, were also identified as unique predictors of maternal reminiscing style. These findings fit well with an ecological systems view of maternal reminiscing as a function of child, maternal, and cultural factors.