EN
A presentation of the institution of sisterhood / brotherhood conceived as a customary establishment of artificial kinship between men or women (posiestrze, posiestrzenie) in Slavonic culture in the light of ethnographic sources from the turn of the eighteenth century to the end of the nineteenth century. The author took into consideration the most important historical sources (A. Fortis, Ł. Gołębiowski, K. Brodziński, A. Brückner, S. Ciszewski) and contemporary studies (J. Boswell, A. Bray, L. Wolff). In this case the titular institution is depicted from the viewpoint of same-gender romantic friendship, comprising an essential binder of a national community.