Objective. Socioeconomic status (SES) has a known influence on academic achievement. Most studies, however, were conducted in English-speaking countries. Because recent cross-linguistic studies suggest that reading English is much harder to learn than reading other languages, an epidemiological study was conducted in French investigating the impact of socioeconomic background on early reading development. Design. One thousand and twenty second-grade children (476 girls and 544 boys) from 20 different schools participated in the study. Approximately 1/3 of the children lived and were schooled in a high SES area, 1/3 in an intermediate SES area, and one final third in a very low SES area. Assessment of reading, writing and mathematical skills was conducted initially in small groups. Children with suspected learning difficulties were further tested individually. Forty-two children of equivalent age who repeated the first grade received similar individual testing. Results. Average reading scores were in accordance with chronological age, without gender differences. Children from low SES schools had academic performances significantly lower than their peers. Boys exhibited superior arithmetic skills than girls. A significant reading delay was observed in 12.7% of children. The prevalence of poor reading was highly correlated with the area of schooling, varying from 3.3% in the high SES area to 24.2% in low SES area. Conclusion. The high rate of children from our sample with a significant delay in reading depended on general socioeconomic environment. An understanding of the origin of such differences is mandatory for defining and coordinating preventive actions and appropriate interventions. (C) 2008 Elsevier Masson SAS. All rights reserved.