This study uses a nationally representative sample of 9-month-old infants and their families from the Growing Up in Ireland (GUI) study to investigate if reading to infants is associated with higher scores on contemporaneous indicators of cognitive development independently of other language-based interactions between parent and infant, such as showing them pictures or talking to them. Reading to infants had an independent positive effect on scores for both the problem-solving and communication subscales of the Ages and Stages Questionnaire (ASQ), while the positive effect of showing pictures was independent only for communication scores. The effects of both of these activities were, however, less substantial than the positive effect observed for the more informal activity of frequently talking to the infant while doing other things; and this was observed for both communication and problem-solving. The analyses were robust to adjustment for several other factors including maternal education, gestational age, non-parental care, breastfeeding, attachment and presence of siblings. The findings highlight the potential of reading and talking to infants, not just for language and literacy development but also for other aspects of cognitive development.