The present study examined gender and age patterns of diminutive use in conversations between 32 Spanish-speaking Peruvian mothers and their three- and five-year-old children. Results confirm previous findings concerning both parents' greater use of diminutives with younger children and children's early acquisition of this complex aspect of morphology. However, findings do not support previous studies on gender differences in parental use of diminutives with young children. Results also revealed that mothers' and children's imitations of their interlocutors' diminutized words promoted their interlocutors' overall diminutive use. This finding highlights the acute sensitivity of both speakers to each others' language and the potential role of imitation in older children's language development.