This thesis analyses the impact of national models (British multiculuralism vs French model of integration) on ethnic salience in youth cultures of working class and immigrant neighbourhoods. It is based on an ethnographic research study carried out between 2007 and 2012, through individual interviews, focus groups and observations among teenagers and young adults in the city of Bondy in Seine-Saint-Denis and the London Borough of Newham, in East London. It shows how both the specifics of national models and of local contexts produce a social, local and fragmented ethnic salience in Newham, and a political and collective one in Bondy. In Bondy, ethnicity overlaps other dimensions of social inequality. The common experience of belonging to a minority results in young people identifying with a close and multidimensional "us" ("blacks and arabs", "youth from the suburbs", "poor people") as opposed to a distant "them" ("institutions", "politicians", "French people"). The central experience of ethnic discriminations tends to saturate young people's relationship to institutions and the way they relate to French society. In Newham, Black, White and Asian young people socialise in their respective groups and meeting places. However, they perceive ethnic divisions as separate to other dimensions of social inequality. Ethnicity is not often politicised or the subject of conflict with local authorities, as it is considered just a part of a larger experience of social injustice. Instead, social class issues are at the core of conflicts between the people interviewed and the wider British society.