Building on the surveys on homelessness initiated by INED and INSEE, the survey on homeless individuals conducted by the OFDT in collaboration with the INPES and the SAMU Social Observatory aimed to explore any specific characteristics of this population in terms of substance use and health behaviors, as this group largely falls outside the scope of traditional quantitative surveys. Furthermore, early French studies on alcohol use among the homeless demonstrated how such behavior can take many forms within populations experiencing precarious living conditions: the 2001 INSEE Homeless Survey showed that while alcohol use among the homeless depended on the diversity of populations and housing situations, it was generally lower than that observed in the general population of the same age. However, these results should be interpreted with caution given the nature of the questions asked, which did not ensure perfect comparability with those commonly used in national surveys [Beck F., et al., (2006), Alcohol Use Among the Homeless: Challenging a Stereotype, Economy and Statistics, No. 391-392, pp. 131–150]. Furthermore, since the survey did not allow for a parallel examination of potential illicit drug use, the profile of drug use among the homeless population remained particularly sketchy.[excerpt from presentation]