This nationally representative study of Irish infants explores whether the set of child and environmental factors established as predicting language outcomes aged 3?years would also predict language and communication development as early as age 9?months. Associations between infant and environmental characteristics and infant language outcomes at 9?months, as measured on the ASQ 10-month communication questionnaire, were explored in a series of bivariate logistic regression models and in a fully adjusted multivariable logistic regression model. Infant gender, health, birthweight and temperament were significantly associated with passing the ASQ communication measure at 9?months. Being an only child and having some experience of relative childcare predicted positive communication outcomes. Infants of older mothers and mothers who spoke less to the child while doing other things were significantly less likely to pass. Infants of mothers with the lowest educational level were more likely than their peers to pass at 9?months. Unlike language outcomes at 3?years, low maternal education does not appear to be a risk factor for poorer outcomes at 9?months. This study adds significantly to the infant language development literature by focussing on communication outcomes in early infancy and identifying protective and risk factors at such an early stage.