This article is devoted to the history of making of the second creed of Sirmium (357) and its doctrinal content. This text is one of the theological manifestos written in the epoch of the Arian controversy. The sources give us little information about the circumstances of composition and the motives of the authors of this document. Hilary of Poitiers attributes this creed to the bishops Ossius of Cordova (one of leaders of the homoousian party) and Potamius of Lisbon. According to his evidence these two bishops wrote the second creed of Sirmium in presence of three Illyrian bishops Ursacius, Valens and Germinius. But the obvious subordinationism of the creed leads the scholars to the assertion that the creed was composed by Ursacius, Valens, Germinius and Potamius, and Ossius only signed it. Modern church historians often connect the proclamation of the second creed of Sirmium with church politics of the emperor Constantius II, who struggled with the homoousian opposition in the western part of Empire. The adoption of such a radical theological manifesto is regarded as a victory of the pro-Arian party. But this interpretation of the creed does not take in consideration the original and inconsistent structure of the text which combines both traditional moderate and untraditional radical theological elements. This fact leads us to the conclusion that the second creed of Sirmium is not a new official theological confession for the whole Catholic Church but includes the traditional and moderate personal confession of faith composed by Ossius (probably in collaboration with Potamius) and the radical commentaries added by Ursacius, Valens and Germinius. After the adaptation by Ossius of a new version of his confession Illyrian bishops restored a Eucharistic communion with him. The central idea of the theological commentaries of Illyrian bishops is that of absolute submission of all creatures to God the Son and of subordination of God the Son in all things to God the Father. Thus, in the theological aspect the second creed of Sirmium can be interpreted as an attempt to stop the theological discussion by the passage from «the theology of substance» to «the theology of relation».