Dependent on welfare, lacking job skills and unable to take care of her infant son, single parent Denise Holmes, who is mentally retarded, tried many times during the past several years to commit suicide. Her last attempt landed her in a psychiatric hospital.

"There was a lot I wanted from life but I didn't know how to get it," Holmes explained.

Today, Holmes, 21, a librarian's assistant for Oliver and Hamilton Inc., a District office services consulting firm, is reaching her life's goals.

Working eight-hour days, earning $4.75 an hour, she is in charge of 4,000 files. She credits her new-found happiness to the District of Columbia Association for Retarded Citizens, which trained her for her job.

"{The association} showed love toward me. This is a big opportunity for me to have my little office and little job," she said. "I've never had the opportunity to work before and I've never been independent before."

She wins raves from her employer. "She's a great worker who puts her best into her job," said Anne V. Hamilton, president of Oliver and Hamilton.

Since 1975, the D.C. organization, a branch of the National Association for Retarded Citizens of Arlington, Tex., has trained and placed 75 to 100 mentally retarded people each year in District jobs. Vincent Gray, the local association's executive director, estimates that the District and the federal governments save $6,000 annually for custodial care for each mentally retarded person they place in a job. Gray said there are 18,000 mentally retarded people in the District, most classified as mildly retarded.

Gray said the association's training lasts a year to 18 months, beginning with a comprehensive evaluation, which focuses on the person's potential, work abilities and job interests.

The association attends to personal adjustment skills such as telling time and budgeting money. "Often these personal skills, and not job skills, determine the length of job training," Gray said.

The D.C. association claims 95 percent success in its trained workers remaining on the job.The agency has devised a new approach to increasing the number of employed mentally retarded persons, especially those previously determined incapable of employment. Gray said the method involves keeping a job coach at the training site until it is determined that the worker can handle the job alone or that it will not work out.

In the past 12 years, Woodward & Lothrop has hired more than 100 mentally retarded people. Fred Thompson, manager of personnel and communications services at Woodies, said that should a problem involving a worker arise, "We have support services with DCARC."

The Washington Hilton has employed mentally retarded association trainees for 10 years. "They are excellent workers, concerned about their job performances . . . . You can count on them," said Barbara Gawronski, the hotel's assistant director of human resources.

Ricardo Thorton, another association trainee, works part time at the Martin Luther King Library, earning $14,500 a year as a librarian technician.

Thorton spent 12 years of his childhood at Forest Haven, the District's facility for the mentally retarded. He and his wife, who is also mentally retarded, have an infant son. Thorton also sits on the mayor's advisory board for the deinstitutionalization of Forest Haven.

Of his work at the library, Thorton said: "My job is interesting because I deal with computers. When I have trouble pronouncing words, I ask another worker to make sure I'm saying them right. I'm working to my full capacity now."