This article has an analytical and theoretical airn, based on the sociological literature sources devoted to the social movements, and it provides an assessment and explanation of the participation by the homeless in both mobilisations and protests. The article analyses why certain homeless people become implicated in the collective actions undertaken and supported by particular charitable associations. It is based on the standard French and Anglo-American research done, along with the more recent studies – both general and more specific – devoted to questions about the homeless and those with no fixed abode.