This paper presents comparative information on the strength of the association between socioeconomic status (SES) and literacy skills at ages 6-8, drawing on data from France, Germany, Japan, Rotterdam (Netherlands), the United Kingdom, and the United States. We investigate whether the strength of the association between SES and literacy skills in early-to-mid childhood depends on the operationalization of SES (parental education, income, or both) and whether differences in inequalities at the end of lower secondary schooling documented in international large-scale assessments are already present when children have experienced at most two years of compulsory schooling. We find marked differences in SES-related inequalities in early achievement across countries that are largely insensitive to the way SES is measured and that seem to mirror inequalities reported for older students. We conclude that country context shapes the link between parental SES and educational achievement, with country differences rooted in the early childhood period.