At court she was known as Mademoiselle de Commercy which was a region within Lorraine.
Despite being from a large group of children Élisabeth Thérèse was the only one who married. That event took place in 1681 when she was wed to Louis de Melun, Duc de Joyeuse and Prince d'Epinoy, Later, Élisabeth Thérèse would add the title of Duchesse de Luxembourg-Saint-Pol to her already extensive collection when she bought the title from Marie d'Orléans. She and her husband went on to have two children.
For Élisabeth Thérèse it had always been her destiny to make her career at court. There she had spent her youth and there she would spent the majority of her life. Her position at court was one of some prestige; she was placed in the service of Marie Anne de Bourbon (a legitimised daughter of Louis XIV) where she would quickly assert herself as a part of the Grand Dauphin's inner circle.
In 1721 Élisabeth Thérèse's fortune was enlarged when her aunt, the Grand Duchess of Tuscany, died and left Élisabeth Thérèse her inheritance. Sadly, Élisabeth Thérèse would have no children to leave her own titles and fortune to; both her children died before she did but her daughter had given her five grandchildren.
When she was not at court Élisabeth Thérèse lived in Paris at the Hôtel de Mayenne. Here both she and her husband would die in 1748.