Earl A. Powell III, director of the National Gallery of Art, discusses Mary Cassatt’s “Eddy Cassatt” with Julie Diehl and Julie Thayer Vehr in the National Gallery of Art’s painting conservation studio. (National Gallery of Art)

When Julie Thayer Vehr went to the National Gallery of Art in the spring of last year to see the exhibition “Degas/Cassatt,” the Middleburg, Va., resident wasn’t just interested in the Impressionists’ show. A great-grandniece of Mary Cassatt, Vehr was scouting the museum as a future home for “Grandpa,” her affectionate name for the Cassatt portrait of her grandfather that had been handed down to her.

“Everybody was so welcoming, and they were anxious to have him there,” she said. “To meet everyone, and see where Grandpa might end up. It was wonderful.”

The visit started a conversation that lasted a year and ended with Vehr and her family donating the 1875 work depicting Col. Edward Buchanan Cassatt as a child.

“He’s a lovely picture, and I love him,” said Vehr, 87. “I’m glad he’s with the gallery now. He’ll be safe and seen by everybody, hanging with other lovely pictures.”

The painting that had hung in Vehr’s dining room for decades fills a significant gap in the National Gallery’s extensive collection of Cassatt works, said Kimberly A. Jones, associate curator of French paintings. It especially complements the “Little Girl in a Blue Armchair,” one of Cassatt’s first Impressionist works.

Mary Cassatt’s portrait of her nephew Eddy was donated to the National Gallery of Art by the family of Edward Buchanan Cassatt. (National Gallery of Art)

“We have nothing from the period before that, when she was trying out styles,” Jones said. Cassatt’s portrait of her nephew Eddy shows “where she was starting from, and the directions she was exploring. It’s ambitious, it is very impressive, but it’s not quite her yet. She was on to something, but she wasn’t quite there.”

Vehr said the painting hung in her great-grandfather’s Philadelphia home before he gave it to his granddaughter, Lois, her mother. Her mother hung it in her Haverford, Pa., home.

“He told my mother he didn’t give it to Eddy because he would have just sold it,” Vehr said. “Mother was told by her grandpa not to sell it.”

She said she isn’t sure why her mother gave it to her, the fifth of six children. “I don’t know why I was chosen,” she said of the gift. “I love art, and I paint and draw myself. Maybe Mother felt I would really not sell it.”

The portrait shows a young boy in a red velvet outfit that Vehr calls his “Little Lord Fauntleroy” suit. “He’s only 5, I think, standing with his whip and his dog and looking very sweet. He reminded me of my mother a lot. She looked like him.”

Jones said the work emphasizes Cassatt’s sensitivity toward children. “She is good at capturing the stiffness, the awkwardness. You know he’s not entirely happy,” she said. “It hits all those marks of the style of portraiture of children of wealth.”

Although Vehr promised her mother that she would never sell it, she and other family members decided to put it up for auction after another Cassatt portrait sold for more than $1 million in 1983. But the market was flooded and the prices dropped, and the painting came back, much to Vehr’s delight.

“Sweet mom had already died when I decided to do that, and anyway, he came back,” she said.

Jones said the work fits beautifully with the other Cassatt works in the museum, including several that were donated by Paul Mellon. “In getting to know [Vehr], we learned that she had met Paul Mellon and they rode the hunt together,” Jones said. “It felt like serendipity. It came about so organically.”

The National Gallery has eight Cassatt paintings on display, including “Young Girl at a Window (c. 1883–1884),” which the gallery acquired earlier this year when it received some 6,400 pieces from the Corcoran Gallery of Art. The museum hopes to have its newest Cassatt on display by early fall.

Vehr said she and her family agreed to the gift, in part for the peace of mind it brings. The painting hung in her house uninsured for many years, she said, and she would wake up in the middle of the night and wonder what she would do in an emergency.

“I kept thinking where would I go first, for Grandpa, or the portraits of my mother or father,” she said. “I’m relieved that he’s safe, and I won’t be the only one looking at him.”