Ida of Lorraine (also referred to as Blessed Ida of Boulogne)^[1] (c. 1040 – 13 April 1113)^[2] was a saint and noblewoman.

She was the daughter of Godfrey III, Duke of Lower Lorraine and his wife Doda.^[3] Ida's grandfather was Gothelo I, Duke of Lorraine and Ida's brother was Godfrey IV, Duke of Lower Lorraine.

In 1049, Ida married Eustace II, Count of Boulogne.^[2] They had three sons and one daughter:

• Eustace III, the next Count of Boulogne
• Godfrey of Bouillon, first ruler of Kingdom of Jerusalem
• Baldwin, second ruler of Kingdom of Jerusalem
• Ida of Boulogne,^{[lower-alpha 1][lower-alpha 2]} has also been postulated. She was married first to Herman von Malsen and second to Conon, Count of Montaigu.

Ida shunned the use of a wet-nurse in raising her children. Instead, she breast-fed them to ensure that they were not contaminated by the wet-nurse's morals, i.e. her mode of living.^[5] When her sons went on the First Crusade, Ida contributed heavily to their expenses.^[6]

Ida was always religiously and charitably active, but the death of her husband provided her wealth and the freedom to use it for her own projects. She founded several monasteries:

• Saint-Wulmer in Boulogne-sur-Mer^[1][7]
• Our Lady of the Chapel, Calais^[1]
• Saint-Bertin^[1]
• Abbey of Cappelle^[8]
• Abbey of Le Wast^[8]

She maintained a correspondence with Anselm of Canterbury. Some of Anselm's letters to Ida have survived.^[9][10]

She became increasingly involved in church life. However, current scholarship feels that she did not actually become a Benedictine Nun, but that she was a "Secular Oblate of the Benedictine Order".^[1][7]

Ida died on 13 April 1113, which is the date she is honoured. Traditionally, her burial place has been ascribed to the monastery of Le Wast.^[7] Her remains were moved in 1669 to Paris and again in 1808 to Bayeux.^[1]

Her life story was written by a contemporary monk of the monastery of Le Wast.^[7]

She is venerated in Bayeux.^[1]