Research findings: No research to date has compared mental state language (MSL) in conversations between children and different adult talk partners, such as mothers and educators. The aim of this study was to investigate the use of MSL (verbalization of mental states such as remembering, knowing and thinking) by children, educators, and mothers during conversations about the past and future. Eighty-five educator-child dyads from seven childcare centers in Sydney, Australia participated in eight conversations that varied by temporal (past/future) and novelty (novel/familiar) focus. Ten educators talked with 40 younger children (27-36 months), and 11 talked with 45 older children (48-60 months). A subsample of 42 mother-child dyads completed the same tasks: 20 with the younger children (27-36 months) and 22 with the older children (48-60 months). Educators used significantly more MSL than mothers. Compared to diploma-qualified educators, degree trained educators were especially likely to use more MSL. Educators' MSL was significantly associated with children's MSL for future talk conversations only. Practice or Policy: Educators' and mothers' MSL may influence children in different ways. Pre-service teacher training appears to facilitate educators' own use of MSL. More research is needed to determine why children use more MSL with their mothers than with their educators. Practice or Policy