The representation of all social groups in political decisions is a basic element of democratic states. While studies on representation used to concentrate on legislative bodies, also the socio demographic composition of the staff of public administrations has far-reaching consequences for the legitimacy and effectiveness of the political system. In contrast to international research, hardly any empirical findings exist about inequalities in the workforce of the public administration in Germany. The article uses institutional and organisational theories to explain the diverse horizontal and vertical representation of women and people with migration background among federal agencies. While increased staff turnover has a positive effect on the representation of the immigrant population, existing diversity policies and the personal commitment of the heads of these agencies improve gender equality. In the coming years, the age structure of the public administration will lead to far-reaching staff restructuring, which should be examined with regard to its consequences for diversity.