Her parents were Bouchard IV/V de Montmorency and Laurette, daughter of Baldwin IV, Count of Hainaut and Alice of Namur. In 1190 she married Simon de Montfort, 5th Earl of Leicester (c 1175 – 25 June 1218), grandson of Simon III de Montfort, who descended from the lords of Montfort l"Amaury, near Paris, France.
Alix also participated in the councils of the crusaders and recruited reinforcements in France. In 1217, she imprisoned the Jews in Toulouse. After this she returned to her family"s estates near Paris.
Another son, Guy, was married to Petronille, Countess of Bigorre, on 6 November 1216, but died at the siege of Castelnaudary on 20 July 1220.
Their daughter, Petronilla, became an abbess at the Cistercian nunnery of Saint Antoine"son Another daughter, Amicia, founded the nunnery at Montargis and died there in 1252.
