New York ? She wrote a book called “Elegance” but don’t be fooled: Kathleen Tessaro has no beauty tips, no fashion advice, no idea how to attain that enviable prize of elegance.

She does, however, know how it feels when “the inner self doesn’t match with the outer self.” That sentiment helped inspire her book, which follows an American woman in London on her journey from frumpy to poised.

The novel, published by William Morrow, follows Louise Canova in the aftermath of a supreme sartorial humiliation — she’s mistaken for being pregnant, when in fact she is simply wearing a baggy dress and has a bit of a gut.

And it all goes down in front of her horrid mother-in-law.

Just when Louise is on the verge of a breakdown, she finds a handy little fashion guide, coincidentally titled “Elegance,” in a used bookshop. In it, she finds an A-to-Z guide to looking and feeling grand.

(Under L — for lingerie — the guide reads: “Nothing betrays a woman more than her lingerie; they are infinitely more revealing than a thousand hours spent on a psychiatrist’s couch.”)

The book helps Louise discover her own unique, elegant self.

Like her heroine, Tessaro is an American living in London. She also found a book called “Elegance,” written in 1964 by French stylist Genevieve Antoine Dariaux, in a used bookstore.

During an interview at the classy and sophisticated Four Seasons Hotel in New York, Tessaro, 38, explains that the discovery of such book was a windfall that deserved a place in its own novel.

“Who doesn’t dream of finding the instruction book to life? In a world that’s sloppy and ill-defined, it’s difficult to find who and what you’re supposed to be,” she says.

Tessaro, who lives with her husband and baby son, says she felt her most inelegant when she was younger and went through “a patch in my life when I didn’t know what to do.”

Born and raised in Pittsburgh, Tessaro moved to London when she was a 19-year-old aspiring actress. She worked in theater, television and “seemed to specialize in bad horror films as the female reporter.”

She was in a bad marriage, too. “I just married the first man I met,” she explains. “He was quite a little older.”

Back then, elegance seemed impossible to attain because “it has to do with someone who reflects on the outside that they’re completely at home with themselves,” she says.

Elegance is an elusive quality, but Tessaro says she knows it when she sees it. Nicole Kidman and Gywneth Paltrow are elegant, as were Grace Kelly and Audrey Hepburn.