Socioeconomic disparities in early language are widespread and have long-lasting effects. The aim of this study is to investigate when social gaps in language problems arise and how they change across the first years of schooling. We address this question in two large longitudinal Norwegian datasets: the Behavior Outlook Norwegian Developmental Study (BONDS) and the Norwegian Mother, Father and Child Cohort Study (MoBa). Despite some slight differences across the two samples, we found that children from higher social backgrounds are less likely to have language difficulties starting from age 18 months and up to age 8 (grade 2). Moreover, while early language problems are strongly predictive of later language, maternal education makes an additional contribution to explaining language difficulties at the beginning of school life. Social inequality in language development arises early, even in a country like Norway, with low unemployment and one of the most egalitarian societies in Europe.