Generally speaking, the number of self-employed workers has risen steadily in the last couple of years. The group of self-employed workers is extremely heterogeneous as it comprises self-employed workers from the liberal professions, persons who are pursuing freelance activities as well as others engaging in low-paid professions. The prototype of selfemployed worker was once by definition excluded from collective forms of the social security system. However, recent years have seen a change concerning the social protection of self-employed workers. Furthermore, unions have tried to organise certain groups of self-employed workers, e.g. freelance journalists. Nonetheless, social partners scarcely represent great parts of self-employed workers due to the heterogeneity of the group.