Recent studies on trade unionism reveal the CGT extending its action, to a certain degree, towards less secure sectors of the employment market, which bear the marks of absent unionist traditions (large retailers, people care, industrial subcontracting...). Within its organisational structure, Local Unions (UL) are supposed to help this extension process. They are designed to welcome employees who work in companies bereft of trade-union institution, faced with their employers, and to help them stand up for their rights. Based on an ethnographic inquiry within two ULs, the present thesis intends to study the ways of commitment and militancy of low and precarious working-class employees (checkout assistants, store shelf stockers, cleaners, nu...