In the Netherlands, as in most other western European countries, the desirability and the governability of a multicultural society are topics of debate. In the last decade, this debate has increasingly centred on second-generation migrants, focusing on their high rates of crime and school drop-out. In the Dutch context, however, little scholarly research has paid attention to second-generation migrants' own experiences. In this paper, I therefore focus on the perceptions of ethnic boundaries held by 12- to 19-year-old second-generation migrants and how they negotiate these boundaries in the low-income, multi-ethnic Feijenoord area of Rotterdam. The study shows that young people are used to living together with many different cultures and see themselves as being on both sides of the ethnic boundary between the Dutch-majority society and the culture of their parents. However, they also encounter prejudice and discrimination in their day-to-day lives, which calls into question the success of multiculturalism.