This prospective longitudinal study examined the relationship between caregiver input to 9-month-old infants and their subsequent language. Mother–infant dyads were videotaped at ages 9, 12, and 30 months. Language comprehension (at 12 and 18 months) was measured by parent report and correlated with an independent language measure. Three maternal style variables were reduced from the 9-month data. Only caregivers' contingent comments (CCC) related to infants' later language. These findings held after infants' skill with coordinated joint attention (CJA) was taken into account. The total number of words the mothers used when their infants were 9 months predicted vocabulary; however, the predictive power was encapsulated in the words the mother used during CCC. Because studies have typically examined maternal input once infants' CJA has emerged, this work contributes to current efforts to understand variations in early language development.