Isarn was the Count of Pallars from 920 until his death, and effectively a sovereign prince. He was the eldest of the four sons of Raymond I, Count of Pallars and Ribagorza. With his younger brother Lope he co-ruled Pallars after his father's death in 920. Their brothers Bernard I of Ribagorza and Miró co-governed Ribagorza. A fifth brother, Otto, was Bishop of Pallars, which allowed the counts, especially Isarn, to effectively control the Church in their territories.