The authors maintain that unsanctioned contio of the Roman people (i.e. contio not summoned by a magistrate) can be considered an important political institute in Roman public life. Special attention is paid to the fact that unsanctioned (unofficial) contiones were held in accordance with customs and laws, to their organization and to their considerable practical importance. E.g., unsanctioned contiones headed by private persons (plebeian leaders) were important factors of political stability in the early republic: they helped to establish peaceful dialogue, they did not contradict laws and traditions and served public interest. Though the authors recognize a high degree of formal organization of official contiones, they argue that it should not be exaggerated. On the other hand, unsanctioned contiones were legitimate, as may be deduced not only from particular accounts of narrative sources, but also from legal sources. As well as a sanctioned contio, an unsanctioned one was well within certain frames of law and tradition. The authors of the paper point out and explain the fact that unsanctioned contio could not be dismissed only by appealing to it, which implied its being recognized as sanctioned. The fact that the XII Tables forbid only night-time unsanctioned gatherings (coetus nocturni) means that other gatherings were not illegal. The sources do not show any other restrictions concerning unsanctioned (spontaneous or not initiated by a magistrate) gatherings under republic. Though assemblies in question were gradually restricted by the law, the process became intense only in the late Republican period; it was only in the Empire that unsanctioned contiones were completely forbidden. Further attention is focused on the terminology used in the sources. Contio was not the only term used to denote official assembly; but the same word was used when an unsanctioned gathering was meant. The authors conclude that in the republican time unsanctioned contiones functioned as an established, important and recognized political institute as well as official contiones summoned and headed by a magistrate. They ensured a legal dialogue between the elite and the masses and helped to develop the principle of representation in the system of public law.