The topic of this JEMS special issue is how the formation of ethnic niches is gendered. We combine theories on niching with those on gendered labour market segregation and show that there are similarities in the underlying processes and explanations. The interaction between niching and gendered labour market segregation takes place at four points. In the first place, entrepreneurship is less of an option for immigrant women than it is for immigrant men. Yet, in some sectors, immigrant women have more options for entrepreneurship than they had in their countries of origin. Their participation in the niche, as workers or as entrepreneurs, strengthens the niche and ensures its continuity. Secondly, women's participation in some niches leads to demands for highly flexible child-care and thus the development of a further niche. In the third place, the concentration of immigrant women in domestic work takes shape as a niche, especially as this sector becomes more ethnicised. The domestic sector, furthermore, is divided into sub-sectors, which leads to niching within a niche. Niches—including domestic work—offer an environment that is regarded as safe, and near to the private sphere. Fourthly, earlier studies have shown how the labour market is divided into a primary and a secondary segment. In the first segment, jobs are fixed and there is a career perspective. In the second, work is flexible and there is no career progression. Immigrants and women are more often found in the second segment. Research presented here indicates that work that is generally regarded as women's work proves also to be accessible to immigrant men. This implies that segregation occurs less between sexes and more between the second and the first segment of the labour market.