OBJECTIVES: We sought to evaluate socioeconomic disparities in serum screening for Down syndrome and assess whether such disparities are more likely to reflect limits in access or information or, rather, informed decisionmaking. METHODS: A nationally representative sample of 12 869 French women completed interviews after giving birth. RESULTS: We found substantial disparities in the likelihood of (1) women not being offered screening, (2) screening not being offered as a result of late prenatal care, and (3) women not knowing whether or not they had undergone screening. Except in the case of nationality, there was essentially no evidence of differences in refusal of testing. CONCLUSIONS: Rather than representing informed decisionmaking, socioeconomic disparities in screening for Down syndrome are mostly due to limits in access or to information.