“This is my favorite book,” Harper, 7, told Cooper, as she began to sit crisscross in front of him. Cooper ran to greet her, wearing a small Santa hat as he sniffed Harper and her book.

Cooper has been listening to children read him stories each month at the library as a part of a program that pairs young readers with therapy dogs — who act as accepting and attentive listeners. Cooper once listened to a second-grader read about 200 pages of “Captain Underpants” for roughly an hour, said his owner, Martha Lester. Some young readers will tell Cooper about the letters of the alphabet they’re learning or flip through picture books.

The Read to a Dog program was piloted at three county libraries over a decade ago, said Dianne Whitaker, a regional manager of the Kensington Park branch in Montgomery County. Now, nearly a dozen libraries participate in the program, including the Quince Orchard, Olney, Gaithersburg and Aspen Hill branches. The sessions — which occur weekly at some libraries — are usually booked with readers who tend to be in the elementary school grades.

The dogs come from volunteers who sign up through organizations, like Pets on Wheels and People Animals Love. Families that are interested can sign up through the library.

The primary purpose is to provide “nonjudgmental comfort” to children so that they feel less nervous about reading out loud, Whittaker said.

It’s a stressful day on Capitol Hill. Dogs are there to help.

During a session at the Olney branch library, twins Liliana and Zoe Tsiolis lifted their hands in greeting for 2-year-old Easton to smell. The 11-year-old sisters were used to being around dogs, since they have two at home and their family volunteers as dog rescuers.

Each had a 10-minute, one-on-one session with Easton. Zoe read a picture book about a group of monsters preparing to scare kids on Halloween, while Liliana read a picture book about different shapes that she picked off a table of suggested books.

Easton laid down as he listened to each of the stories, occasionally lifting his head as they read aloud. After their session, Zoe said watching him lift his head and look up at her was her favorite part. The twins both agreed that reading to Easton was better than reading to people.

“I don’t feel that nervous,” Zoe explained.

Easton’s owner, Jennifer Miller, said that he enjoys having the children around him during the sessions. “He’s happy to be here and be pet,” she said.

No one wanted Princess Fiona. Then the balding, potbellied pitbull met a little girl.

The program’s parameters vary by library. The Olney branch invites families to sign up in advance for a 10-minute session, though occasionally an impromptu walk-in reader can come in on a less busy day. Olney’s organizers facilitate the program about once each week. At the Long Branch Library, there is no required registration. The library hosts the program about once a month.

At Long Branch, Harper had been reading about different states to Cooper for about 4o minutes. She read him facts about Ohio, including that seven U.S. presidents who were born in the state, before she came across a word she didn’t know: “buckeye.”

“Buck-ey?” she pronounced.

Her mother, Stephanie Powell, said, “Buck and then E-Y-E. That’s a word that you’ve seen differently, like on it’s own."

Harper sounded the word out again. “Buck-ay?” Cooper was sitting in front of them, patiently wagging his tail. She then tried, “Buckeye," and grinned when she realized she got it right.

Occasionally she would take a break to feed Cooper a treat or try to help her 16-month-old sister Vera gain the courage to say “hi” to the dog.

When asked after if she thought Cooper was a good reading partner, Harper exclaimed, “He listened!" She leaned down, pet him some more, and he started panting.

It was time for another story.