Introduction: The number of homeless families has risen sharply over the past decade in France. Little is known about the sociodemographic and health characteristics of this population. The Paris Samusocial Observatory conducted a study, one of the objectives of which was to estimate vaccination coverage (VC) among homeless children. Methods: A cross-sectional survey conducted in the Île-de-France region on a sample of 801 families residing in social housing, emergency shelters, social reintegration centers, or shelters for asylum seekers. Children under 13 years of age were selected using a three-stage random sampling method. Vaccination data were collected by a nurse from health records during face-to-face interviews. VC was defined as the ratio of the number of children vaccinated with a given vaccine to the number of children included in the analysis. The association between vaccination and sociodemographic variables was analyzed using Poisson regression. Results: A total of 751 children were included between January and July 2013. Among homeless children born in France, vaccination coverage rates were generally high (>90% at 24 months of age for most vaccinations) and similar to those observed in the general population, whereas those among homeless children born outside France were significantly lower (all <50% at the same age). At 24 months of age, the probability of being vaccinated for a homeless child born in France was generally 2 to 14 times higher (depending on the vaccine) than that of a child born outside France (p<0.001). In the latter group, vaccination coverage improved after 24 months, but catch-up vaccination remained insufficient. Conclusions: Although it is possible that part of the observed gap is related to a failure to record vaccinations administered before arrival in France, these data suggest that homeless children in the Île-de-France region born abroad are less well vaccinated, at the same age, than other children. Particular attention should be paid to this specific population.