Used a cross-sectional natural language database to investigate the parent-child conversations of 3-, 4-, and 5-year olds. Found that 4-year-olds and, to a greater extent, 5-year olds reliably used explicit contrastives. All the children regularly elicited mentalistic responses from their parents and, in some cases, these parental responses were positively related to children's production of mental talk. (Author/KB)