This paper discusses how social categorizations can be of fundamental importance for power relations in intergroup relations during an implementation of cultural diversity in a work organization. One purpose is to present a conceptual bridge between Michel Foucault´s concept of power and Henri Tajfel´s Social Identity Theory. This is done through a conceptual synthesization of Foucault´s concepts hierarchical observation, normalizing judgment and examination and, Tajfel´s concepts social categorization, social comparison, and social identity. Another purpose is to illustrate the conceptual synthesization by analyzing personnel statistics from and interviews at a Swedish hospital and a truck factory. The findings show that cultural diversity would not only be a question about increased awareness or change of attitudes: it is also about a critical questioning of more complex and often invisible normal conditions in terms of particular aspects that cause subtle conflicts in intergroup relations.