Stephen married a daughter of Robert I of Capua, in the early 1120s. Historian Paul Stephenson wrote that Stephen's marriage alliance with the Normans of Southern Italy "... must have been partly directed against the Venetians." The Norman princes of Capua had been the pope's staunch supporters during the Investiture Controversy, suggesting that his marriage also continued his father's pro-Papal foreign policy. According to Włodzimierz Dworzaczek, Stephen in 1121 married Adelhaid, daughter of Heinrich, burgrave of Regensburg.