CONTEXT: The design and evaluation of adolescent health programs rarely account for socioeconomic differences in reproductive health needs and service utilization among young women in developing countries. METHODS: Nationally representative Demographic and Health Survey data for 12 developing countries were used to assess socioeconomic differentials in reproductive health outcomes and service utilization among young women. For each country, chi-square tests were performed to identify statistically significant differences between the poorest and the richest quintiles, which were constructed using a household wealth index. RESULTS: In most countries, young women from the poorest households were more likely than those from the richest households to be married by age 18 and to have had at least one child by that age; they were less likely to report a mistimed birth, to be practicing contraception, to use maternal health services and to know how to prevent sexual transmission of HIV. Economic autonomy, school enrollment and regular exposure to mass media were less common among poor than among rich adolescents. CONCLUSIONS: Poor adolescents may be overlooked by current service delivery modes that rely solely on mass media, clinics or schools. Alternative strategies, such as community-based outreach programs, must be implemented to serve the needs of poor young women