Modern France has encountered two main critical junctures with regard to ethnic/racial identity: the liberation of France from the Vichy regime at the end of WWII, in 1944; and the oil crisis of 1973, at which point it shifted from welcoming immigrants to turning them away.
The end of WWII brought two concurrent events: the fall of the Nazi collaborationist Vichy regime, and the increase in immigration from French colonies in North Africa, Sub-Saharan Africa, and Southeast Asia to France. France welcomed and encouraged this immigration flow of both guest workers and their families (Bleich: 2001). French economic success made this influx of immigrants welcome, even necessary (Giry: 2006).
The oil crisis of 1973, however, brought an end to decades of relative prosperity, and in 1973 the French government largely halted this immigration into the country. Some suggested that existing immigrants be forced to leave by refusing to renew residence agreements; other, however, argued that immigrants living in France should be offered citizenship for themselves and their families. The latter argument prevailed, but the overall policy of the government shifted from encouragement to deterrence of immigration (Giry: 2006) (Guiraudon 1-2: 2002).