The contributions of mothers' and children's oral language to children's school readiness were longitudinally examined among 75 low-income mothers and children. When children were 36 months, mothers' and children's lexical diversity, mothers' wh-questions, and children's PPVT-III scores were assessed from play interactions. At pre-kindergarten, mothers and children shared a personal narrative, and various aspects of mothers' and children's narratives were coded. Children were assessed on their knowledge about print, letter-word identification, mathematical skills and sustained attention, and scores were combined into a single factor of school readiness. Structural equation analyses yielded two pathways to school readiness. Mothers' wh-questions and lexical diversity predicted children's PPVT-III scores at 36 months, which in turn predicted children's school readiness. Mothers' 36-month lexical diversity predicted mothers' narrative prompts, which related to children's narrative contributions. Children's narrative contributions in turn predicted school readiness. Mother-child conversations support the school readiness of children from low-income backgrounds. (Contains 2 figures and 2 tables.)