The account of his life, written by his disciple Albert, who lived with him during his last year at Maleval, has been lost.

Written accounts of his life by Theodobald, or Thibault, given by the Bollandists, is unreliable because it has been interpolated with the lives of at least two other Williams.

[2] After a number of chapters in which Theodobald confuses him with St. William of Gellone, Duke of Aquitaine, he says that William went to Rome, where he had an interview with Pope Eugene III, who ordered him to make a pilgrimage to Jerusalem in penance for his sins.

[1] Though Theodobald's account of his interview with the pope does not carry conviction, the fact of this visit and his subsequent pilgrimage to Jerusalem is supported by excerpts from the older life, which are preserved by responsories and antiphons in his liturgical feast Office.

He was prevailed upon to undertake the government of a monastery in the area, but being unsuccessful in attempting to reform the monks tepidity and indolence, he retired first to Monte Pruno,[3] and finally in 1155 in the desert valley of Stabulum Rodis, later known as Maleval, in the territory of Castiglione della Pescaia, Diocese of Grosseto,[4] where he was joined by Albert.