The paper is divided into two parts. The first part explains the concept of solidarity and fraternity on a theoretical level, especially in the light of Catholic social teaching. The second part analyzes the principles of solidarity and fraternity in Croatian society during the National Federal Republic of Yugoslavia and the Socialist Federal Republic of Yugoslavia. In addition to solving the national question under a specific aspect of brotherhood, this term was understood in the spirit of the communist ideology of brotherhood and unity of the Yugoslav peoples, and the ideology of solidarity was present predominantly in the form of self-governing socialism. The paper, therefore, shows how socialist Yugoslavia had many characteristics of a totalitarian system defined by communist ideology. Rad je podijeljen na dva dijela. U prvom dijelu objašnjava se na teoretskoj razini, osobito u svjetlu katoličkog socijalnog nauka, pojam solidarnosti i bratstva. U drugom dijelu, analizira se primjena načela solidarnosti i bratstva u hrvatskom društvu u vrijeme Federativne Narodne Republike Jugoslavije i Socijalističke Federativne Republike Jugoslavije. Osim rješavanja nacionalnog pitanja pod određenim vidom bratstva, ovaj pojam je bio poiman u duhu komunističke ideologije bratstva i jedinstva jugoslavenskih naroda, a ideologija solidarnosti osobito u obliku samoupravnog socijalizma. Rad, stoga, pokazuje kako je Socijalistička Federativna Republika Jugoslavija imala mnoge oznake totalitarnog sustava koji je bio određen komunističkom ideologijom.