Objective. From an original large sample of 1062 7 to 8-year-old children, reading skills were assessed and found to be highly linked with socioeconomic status (SES). The purpose of the present study was to further determine underlying medical, sociocultural, cognitive and behavioural factors explaining the diversity of reading skills and the influence of SES. Method. Individual testing among low-SES children identified 100 poor readers, 50 typical readers and 31 children with intermediate reading scores. All 3 groups underwent a thorough assessment, including a medical evaluation, a full cognitive battery, a structured parental interview and behavioural questionnaire. Logistic regression was used to demonstrate the variables predicting reading score outcome. Results. None of the medical factors studied was statistically related to reading scores. Due to the methodology buffering the impact of SES sociocultural variables, such as parental levels of education, parental occupation, as well as familial income were weak, but statistically significant predictors. The strongest variables were phonological abilities and symptoms of attention disorders. In a final regression model, phonological awareness, level of mother's education and attention explained the differences in reading skills. Conclusions. These results, which are unique in France, are similar to existing data in the literature. They support the need to conceptualize an early screening programme to detect reading difficulties and to promote an intervention based on phonological processing and decoding in low-SES environments. (C) 2008 Elsevier Masson SAS. All Lights reserved.