Over the last few years, social investment has been at the centre of the debate on how to deal with the crisis of the European social model. The notion of social investment is based on the idea that social problems can be dealt with and inequality can be counteracted by investing in the human capital of disadvantaged individuals and groups. Against this background, the objective of this contribution is to assess the adequacy of the social investment strategy in facing the challenges posed by a multicultural society, by looking at the example of active labour market policies. Relying on meta-analytical research, it shows that access biases to policy measures as well as labour market discrimination severely limit the potential of a social investment strategy to deal with the problem of mainlining social cohesion in increasingly diverse societies. The chapter concludes by arguing that social investment and particularly active labour market policies must be adapted to the emerging European multiethnic societies, otherwise they will fail to deliver on the promise of maintaining social cohesion.