This chapter describes and analyses French trade unions’ attitudes and actions towards immigration and migrant workers during the past two decades. In terms of immigration, France is nowadays in median position in Europe, with foreign-born persons accounting for 11.6 per cent of the resident population in 2009–10, but a migrants’ direct offspring that is more numerous – though less visible – than immigrants themselves. Under the influence of the surge of the Front National, an unwelcoming climate and restrictive immigration and integration policies have become dominant characteristics of the context in which trade unions have dealt with migrant workers. While French trade unions had a long tradition in organizing migrant workers, they appear less able to play a key role in the process of migrant workers’ integration in a more competitive, flexible and segmented labour market. The trade unions’ practice of using the principle of equality as their main weapon leads to significant trade union support action for migrant workers, who nonetheless lack or have a weak legal status.