SOUTHEAST — Thirteen-year-old Leila Johnson gently pets Patrick, a chestnut brown thoroughbred she has just finished riding. The large horse, used mostly to teach sport-riding skills, leans in and whinnies at her affection.

The tender bond between Johnson and Patrick is visible as she completes another invigorating lesson at Pegasus Farm. Horseback riding, she agreed with a smile, makes her feel strong and happy. Johnson is learning-disabled with low verbal skills and a muscle disorder.

"Leila loves it here. It's the highlight of her week," said her mother, Kim Johnson. "She's gained confidence and her muscle tone is improving. Riding is teaching her to follow directions and to communicate."

Like Johnson, countless children with physical and developmental challenges have benefited from programs offered through Pegasus Therapeutic Riding. Now in its 32nd year, Pegasus, which has several chapters in the region, has another reason to celebrate.

The venerable organization recently opened a headquarters on Peach Lake Road in Southeast, close to the North Salem border. The idyllic 20-acre expanse is nestled among rolling hills and overlooks picturesque Peach Lake. It once was the home of New England Equine Practice, a horse hospital that moved to Patterson this year. An anonymous donor gave Pegasus the $2.1 million needed to purchase the property.

"Pegasus has been looking for its own facility for 10 to 15 years. You could call it good luck, but I think the donor stepped forward because the program works," said Jean Smith, director of development. "There is so much more you can do when you have your own place."

The facility is open six days a week with three classes per day. There are plans to increase its adult programming and to construct an indoor arena that will enable year-round riding lessons, Pegasus officials said.

Behind the organization's administrative offices, volunteers have been clearing 3 to 5 acres of wooded area to make way for a sensory trail system that will give students the opportunity to experience riding on undulated terrain. The trail will also have activity stations to incorporate music and touch-therapy games.

"This will assist kids with balance and posture problems and with tactile sensory development," said Colin Riley, Pegasus' communication officer. "It will provide a whole other arena to therapeutic riding."

A notable aspect to the new facility is that the horses themselves will have the space to roam free and graze.

About a dozen horses now live at Pegasus Farm. The added land gives Pegasus the opportunity to expand its herd.

"Horses will now be able to go out and play and unwind after they've been working," said Smith.

Pegasus was formed in 1975 at the Ox Ridge Hunt Club in Darien, Conn., by a group of volunteers who believed strongly in the science and therapeutic value of horseback riding.

Since then, the organization has offered its programs through some six farms in Westchester and Fairfield counties, serving about 200 students per year. Pegasus plans to keep its other chapters open, officials said.

"There's something about the movement of the horse that is very calming that enables you to stay focused," Smith said. "I find it inspiring when, for example, a little girl who uses a wheelchair gets up on a horse. I think it changes the way people perceive themselves."

There is approximately a two-year waiting list for lessons, though wait times can vary depending on rider and horse compatibility.

Students are paired with an instructor and about three volunteers who walk alongside the rider. At Pegasus Farm, riders are led around several paddocks, some trotting and posting.

"Each child has an individual program plan," said program director Betsy Medinger. "We always want students to act as independently as possible."

Luke Howlett, 15, has been with the program for about four years. Howlett, who has developmental delays and is nonverbal, has profoundly benefited from the experience, both physically and emotionally, his mother, Laurie Howlett, said.

During a session this week, Howlett arrived to discover that Toby, the horse he normally rides, was in the stall with a bruised hoof. Before he could ride Rio, a quarter horse, Howlett paid Toby a visit, showering him with tiny kisses and soft pats. Howlett keeps an 8-by-11-inch photo of Toby in his room and won happiest rider at this year's Pegasus horse show, his mother said.

"Horses are the great equalizer. ... He feels so proud of himself in a way that no other therapy can do," she said. "When you're riding, life isn't hard and you're not different."