This is Texas, isn't it?

And there are few horsier spots in Texas than the Richmond State School in this town 30 miles southwest of Houston, where a therapeutic riding program using horses retired by the Texas prison system has helped hundreds of severely retarded residents in state care learn basic skills like walking and communicating.

So when the Houston Dressage Society, which is dedicated to the equestrian training arts, came to the school Monday for some four-footed pas de deux in its second annual "Nutcracker on Horseback" with highlights from Tchaikovsky's "Dance of the Sugar Plum Fairy" and "Waltz of the Flowers," the audience fell into awed silence and then raucous applause.

No horse executed a grande jeté into another's embrace. But the six dressage riders in Santa hats and holiday finery, and their shining mounts with colorful leg wraps - Rhonda Smith and Wimbledon, Martha Guyton and Absolute Lee, Sarah Schaller and Cash, Marie Morgan and Yosemite, Cindy Franchek and Greystoke, and Fran Dearing and Mackinaw - pranced rhythmically to the music.

Some of the loudest cheers were reserved for two of the school's own: Kevin Johnston, 44, riding Rowdy, and David Anderson, 41, atop Holli, who both joined the dressage company in a finale, "Procession of the Nobles."

"When he came here 11 years ago he could not sit on a horse," said Mr. Johnston's mother, Janice. "Now he's riding with the rodeo." He has won several prize buckles in the special-events competition of the annual Houston Livestock Show and Rodeo, Ms. Johnston said.

Of the school's 530 residents, who range in age from 18 to 92, about 50 have been selected, based on ability, for therapeutic riding, said Jesse Gonzales, the program's manager.

"It's a slow process," Mr. Gonzales said of their progression, "but we have a lot of patience."

Reva Williams said her daughter, Kimberly Harrison, 40, had been at the school since she was 6. "That's how she learned walking, by riding a horse," Ms. Williams said, adding: "People don't realize that horses and humans have the same rhythm of walking. It triggers something in the brain."

Before the Richmond school adopted its riding program in 1990, it took residents to a stable in Galveston. Now the school has a large riding arena on its 241 acres.

Therapeutic riding, which originated in Europe and began catching on in the United States in the 1950's, has grown to about 500 programs in this country, according to the school. In addition to the physical benefits, it says, people with mental and emotional disabilities can gain increased confidence by interacting with animals.

In this case, the horses also benefit. They are given to the school by the Texas Department of Criminal Justice after they are no longer useful for mounted guard patrols or cattle drives in prison ranch programs.

"The Nutcracker on Horseback" was the idea of two friends on the hospitality committee of Houston Grand Opera: Ms. Guyton of the dressage society and Ileene R. Robinson, whose sister, Rita Sue Rosenfield, is a longtime resident of the school. Ms. Robinson also encouraged the residents to study the campus landscape, covered with pecan trees, and to build large cardboard nutcrackers, which decorated the arena.

Relatives of residents praised the state's care as exemplary but voiced concern that budget cuts might shrink the number of schools. Texas ranks 46th among the states in mental health spending per capita, according to an annual survey by State Senator Eliot Shapleigh.

Officials from Austin attended the performance, among them Scott Schalchlin, director of state mental retardation facilities; State Representative John E. Davis of Houston; and a representative of Gov. Rick Perry.

Mr. Johnston, one of the resident riders, was nervous to hear that his parents had come to cheer him on, but clutched them afterward in a tight embrace.

"We're very proud of him," said his father, Graham, a swimmer at the 1952 Olympics who this October, at the age of 74, swam the Strait of Gibraltar from Spain to Morocco in 5 hours 9 minutes.