When kids stop by therapist Richie Calvin's office these days, they are greeted by not one but two friendly faces. The second belongs to his newest partner -- a gentle, bright-eyed Labrador-golden retriever mix named Tahoe.

Tahoe is more than just a pet to the residents and staff at Graydon Manor, a Leesburg inpatient psychiatric center that cares for about 45 emotionally troubled youngsters. In the four weeks since she arrived, the 2-year-old dog has been able to give what no human can -- unconditional love, trust and affection to the children who need it most.

"I've had kids say to me, `You're only nice because you're paid to be nice,' " said Calvin, who has worked at Graydon Manor in southwest Leesburg for more than a decade. "But with dogs, it's all natural. There's nothing fake about it."

In return, Tahoe gets back what she gives and more. Everywhere she roams, the kids take notice, calling out "Hi, Tahoe!" from across the paths and fields.

At times, the dog is surrounded by multitudes of children, all of whom want their turn to hug and stroke her. It's a lot of attention to deal with, but Tahoe rarely flinches.

She's exactly the kind of dog Calvin wanted when he started searching for a pet about a year and a half ago.

Calvin knew he didn't want just any dog. He wanted a dog who could accompany him to work every day and was specifically trained to remain calm in a crowd.

So Calvin turned to the group Canine Companions for Independence (CCI), which provides various types of trained dogs to assist people with disabilities and help professional caregivers in their work. The Santa Rosa, Calif.-based organization has placed about 1,500 dogs nationwide since it was founded in 1975.

Initially Calvin's boss, Bernard Haberlein, wasn't sure that bringing a dog onto the facility would be a good idea.

"I thought, `Oh my God, do we need this?' " said Haberlein, executive director of Graydon Manor.

"But after I talked with Dr. Calvin and saw how sincere he was, and after I took a look at the literature, I thought it was worth a try."

Once Calvin received the go-ahead, he underwent a grueling application process with CCI, which included extensive questionnaires, multiple reference checks and long interviews. It was almost like "adopting a child," Calvin said.

Most of CCI's dogs are placed with individuals rather than facilities, which require dogs with especially good social skills and temperament, said Rob Manaseri, development manager for the organization's Northeast Regional Center.

Graydon Manor fit all of the criteria to receive a CCI dog, Manaseri said.

"It was a perfect match," he said. "They had the know-how and the ability to receive and care for one of our dogs properly."

Once CCI found a dog for Calvin, he drove up to Farmingdale, N.Y., to participate in a two-week training course, in which he learned how to give commands and interact with Tahoe.

Tahoe now accompanies Calvin, 52, throughout his day, from the moment he wakes up in his Ashburn home to bedtime. Having a dog constantly by his side has changed his personal life as well as his professional life, he said. Calvin and his wife, who have no children, have come to regard Tahoe as family.

"I think of her as a real treasure," Calvin said. "It's very much like having a child. There are some tasks that are enjoyable, like walking her, and there are some that aren't, like cleaning up after her. The biggest problem is getting it all done. So you have to be much more organized."

At work, Tahoe sports a royal blue vest with the words "Canine Companions for Independence" and is never far from Calvin during therapy sessions, leisurely strolls around Graydon Manor and plays games of catch on the tennis court, where she dashes after every ball thrown for her.

Calvin says Tahoe's very presence has helped calm his patients, who often must recall painful memories during therapy. During one recent session, a teenage girl cradled Tahoe in her arms while telling Calvin of the sexual abuse she experienced.

Tahoe can also help reveal a child's innermost thoughts. As a 15-year-old girl watched several of her friends play with Tahoe, she said wistfully, "I wish I was her. Then I'd get all that love and attention."

Tahoe's performance at Graydon Manor will be evaluated by CCI after 90 days. Then, a CCI representative will visit the dog and owner annually to make sure everything continues to go well for them and the youngsters. So far, Haberlein said, he is pleased with how Tahoe has been integrated into life at Graydon Manor.

The idea of incorporating specially trained pets into facility settings such as Graydon Manor is growing in popularity, said Manaseri, of CCI.

"People are learning a lot more about the benefits of having an animal interact with people who are disabled or ill," he said. "It seems to speed up healing time. It opens doors for many people."

CAPTION: For Richie Calvin, right, a therapist at Graydon Manor, as well as for his young patients, Tahoe has brought a new measure of love and affection to life at the psychiatric center in Leesburg.