Victories are won every day in a muddy riding ring in Rock Creek Park. Some of the triumphs are as slight as learning to sit quietly for a few moments. Others are more momentous: A child who has never learned to talk may suddenly join in a song, or one afflicted with cerebral palsy may gradually straighten up and learn to walk without leg braces.

At the National Center for Therapeutic Riding near Military and Glover roads, an untutored observer sees adults and children learning to ride horses. But a more informed look reveals the victims of a variety of crippling conditions battling their handicaps and winning.

The 140 handicapped persons--most of them children--who come to the center to ride have problems ranging from physical disabilities to severe mental retardation. Learning to ride a horse is not the purpose, said the center's founder, Robert Douglas, a former virologist at the National Institutes of Health.

"We're not trying to teach these kids to be good riders. We're trying to teach them fine and gross motor control, spatial judgments, language skills," he said. "We're also trying to make them good citizens. Education is a big part of what we do here."

Anna Persons, a teacher of retarded deaf-blind students at the District-run Sharpe Health School, said horseback riding is "very helpful" to her students who attend the center. "It gives them a sense of accomplishment, and an unusual sense of independence.

"In this population, you usually don't see immediate progress," Persons said. "It may take years for a student to learn to do something, but with horseback riding, they seem to learn what to do very quickly." She said that riding helps youngsters overcome fear of new situations in general and that they seem to retain what they learn about horses, even though they go to the center only eight weeks a year.

Another Sharpe teacher, Robyn Falkner, whose students are also retarded, said: "I have students who have almost no language skills, but they have learned to anticipate that Monday is horseback riding day. They are excited to be there. They show that by jumping up and down, by squealing, and big grins."

In early December, Cindy, 15, a special education student at Hamilton Junior High School in Northeast, won her own victory. With the help of a volunteer and the urging of classmates, Cindy for the first time experienced a riding technique called going "around the world." That is, she made a 360-degree turn in the saddle, an exercise that involved letting go of the reins, kicking her feet out of the stirrups and balancing on the saddle while throwing her legs over the horse's neck and rump. This is no small feat for a person who had not ridden before. Fellow students yelled encouragement from their own horses and gave her a big round of applause after she finished.

"That was a great accomplishment for her," sid Martha Black, the volunteer coordinator at the center. "Alice Stewart, the riding instructor set it up so she was the only one who hadn't done it. Then all the other kids were watching her and she had to do it."

The center's successes with mentally retarded persons are even more dramatic. Last summer and fall, 11 adults from Forest Haven, the District's institution for the mentally retarded, came to ride for 10 weeks.

The students were labeled "profoundly mentally retarded." Of the 11, seven could not talk, and most needed help with dressing, bathing and eating. Yet they all learned to sit on a horse, follow simple commands such as "Touch your head. Touch your foot. Lean forward and hug the horse's neck." A few learned to trot.

"It was such a fantastic thing. The first session they were scared to death. The second session some of them were sitting on the horse, using correct posture and running to get on the horse without assistance," said Shirley Reese, a unit manager at Forest Haven who suggested the activity.

Reese recalled that one student, Richard, who always repeats everything that is said to him, broke out of that pattern when the instructor asked him if he wanted to get on the horse. He had never answered a question before.

"He said no. It was great," Reese said, laughing.