The number of families living in shelters in the Paris region (France) has increased by a factor of three in 10 years. In 2013, a survey was performed on homeless families in order to characterize their living conditions, their health needs, and the developmental problems in children. This probability survey was conducted in 17 languages among 801 homeless families sheltered in emergency centers for asylum-seekers, emergency housing centers, social rehabilitation centers, and social hotels in the Paris region. Among the 772 families that provided data on food security only 14.0% were with food security, whereas 43.3% were with low food security and 9.8% with very low food security (a situation where children are also affected). Stratified multivariate robust Poisson models showed that some characteristics are associated with a higher risk of food insecurity and/or of falling into very low food security, such as residential instability, single parenthood, having more than three children, depressive symptoms, housing in social hostels, and difficult access to cheap or free food locally. Given the wealth of the Paris region, resources and programs should be concentrated on improving the living situation of this vulnerable population. It needs better detection of these families, a closer social follow-up, and an increase in food aid.