Children’s exposure to talk about conceptual categories plays a powerful role in shaping their conceptual development. However, it remains unclear when parents begin to talk about categories with young children and whether such talk relates to children’s language skills. This study examines relations between parents’ talk about conceptual categories and infants’ expressive language development. Forty-seven parent-infant dyads were videotaped playing together at child age 10, 12, 14, and 16 months. Transcripts of interactions were analyzed to identify parents’ talk about conceptual categories. Children’s expressive language development was assessed at 18 months. Findings indicate that parents indeed talked about conceptual categories with infants and that talk was stable across time, with college-educated parents producing more than non-college-educated parents. Further, parents’ talk about conceptual categories between 10 and 16 months predicted children’s 18-month expressive language. This study sheds new light on mechanisms through which early experiences may support children’s language development.