Maria Gillis is an effervescent 21-month-old child who is nearly ready to walk and already has begun talking. She is a great actress, especially when her teachers and her mother Yvonne reward her with applause. If you tell her she is a "good girl," she claps her hands with delight and is more than happy to entertain you again with her antics.

Maria has Down's Syndrome -- also known as mongolism -- a genetic disorder that results in mental retardation and lack of muscle tone and coordination. Many Down's Syndrome babies also have serious heart problems. The syndrome usually is recognized early in life by the babies' apparent lack of energy, slanted eyes and enlarged tongues.

Part of the reason for Maria's steady development is IMPACT, a federally funded training program for Down's Syndrome babies at Howard University.

IMPACT, which stands for Interdisciplinary Model for Parent and Child Training Program, trains parents in "infant stimulation," a series of individualized exercises to teach Down's Syndrome babies patterns of movement that normal infants pick up naturally. Down's babies usually develop motor skills two or three months behind normal babies.

The exercises involve applying pressure to joints and muscles to help the children learn how to move from one position to the next, explained Norma J. Hall, IMPACT's head teacher. For example, a baby may be placed on its hands and knees, and coaxed into moving a hand, then a leg.

"We like to get them as early as six weeks," said Debra Byrd, an assistant teacher.Children who are not stimulated early will vegetate, Byrd said.

The program is being offered to 15 infants free of charge. The training includes one 90-minute office session each week plua a 90-minute session in the home.

Home visits are designed to build parents' skill and confidence in working with their children. "The parent is the first teacher," Hall said, adding that while 80 percent work hard with their babies, the other 20 percent are uncomfortable with their abnormal child and must be motivated by scolding from IMPACT staff. "Training makes all the difference," she said, and parents must learn to reward as well as discipline their children.

IMPACT is for children like Maria Gillis and David Shorter.

David, 11 months, was diagnosed as a Down's Syndrome baby right away. He is very small and has two heart defects that will require surgery in the next year. Social workers at Columbia Hospital for Women, where David was born, told his mother, Terri Shorter, about IMPACT. David has been enrolled since he was 6 weeks old.

Terri said she is very pleased with her son's progress. She was worried at first, but said that "judging from the literature I've read, I realized he would have been doing worse (without training)." At 11 months, doctors say, the child has progressed to the level of an 8- or 9-month-old child.

Terri works with David for about 90 minutes each day. He is now learning to crawl, his mother said, "but he's afraid to move his leg and arm together."

IMPACT teachers believe that after 18 months of age, one-on-one interaction is no longer valuable to Down's Syndrome babies. As toddlers, children begin learning by imitating and interacting with each other.

So the District's only training program for Down's Syndrome babies and their parents is preparing to expand to include a preschool program.

By September, the university's IMPACT project hopes to have space for 12 children who are older than 18 months, according to Rosa Trapp-Dukes, director of the project. The project is part of the university's Child Development Center.

Classes will be designed to work on motor skills, speech and improving attention span.

Continuation of the learning process is what makes the planned preschool program so important, according to Byrd. At least seven of the students in the preschool program will be toddlers who began with IMPACT as infants.

Down's Syndrome occurs in one of every 800 births, although new studies suggest this trend may be dropping to one in 1,000 births.

Medical science has never fully understood why the chromosome abnormality that causes Down's Syndrome happens. Babies with the syndrome are nearly 10 times more likely to be born to mothers over 35.

Ten years ago, most Dawn's babies were put in institutions shortly after they were born, but lately it has been shown that with early training and a supportive home environment, these children can do quite well. Most are able to reach the mental age of a 10-year-old.

Before this program, Down's Syndrome babies could receive only day care until they were old enough to enter special classes in elementary schools.

Byrd said she believes that without continued training, the children will regress and forget what they have learned before they get into kindergarten or first grade.

Trapp-Dukes said she is hopeful that the success of IMPACT and the preschool program will prompt private sources to continue funding when the three-year federal grant runs out next July.