Brigitte Macron, the wife of French President Emmanuel Macron, is getting an official role but without the title "first lady".
The presidency has published a "transparency charter" defining her duties, funded from Mr Macron's budget.
She will have an active role in civil society, focusing on disabled people, education, children, women's issues, health and gender equality.
A petition signed by more than 316,000 people opposed a "first lady" role.
Much French media comment has focused on the 24-year age gap between her and her younger husband. She played a prominent role in his election campaign and is seen as a strong influence on him.
The social issues that will particularly engage her also figured as priorities in Mr Macron's manifesto.
The Elysée Palace's new "charter" (in French) is an innovation - no previous French presidency has stated the spouse's role so clearly.
Creating an official first lady position would have required a change to the law or constitution. Instead, the charter uses the term "the head of state's spouse".
It stipulates that Mrs Macron will not be paid a salary for exercising her duties, nor will she have her own budget or expenses claims. The costs will come out of the presidential budget.
She will have the assistance of two advisers, her own office and a secretariat.
In his presidential campaign, Mr Macron stressed that politicians should not employ relatives, after his conservative rival François Fillon lost much support for doing so.
In an interview, Elle magazine asked Mrs Macron how she had reacted to hostile and sexist comments on the age gap between her and Mr Macron. She answered: "Badly - but finally I told myself: 'Well, you're having a hard time, but just keep quiet about it.'" She added: "In time, it goes away".
She admitted that her love for Mr Macron had caused some private anguish.
"The children often suffer. I know I caused some harm to my children, and that's the thing I reproach myself for most of all. But I couldn't help doing what I did. There are moments in life when you have to make vital choices."
On the age gap, she said: "So regarding the 20-year gap, whatever could be said about that was so petty. Of course at breakfast I sit there with my wrinkles, he with his freshness. But that's just the way it is."