Mother Teresa; a five-foot nun who has devoted her life to the poorest of the poor in Calcutta, was awarded the Nobel Peace Prize today.

The tiny, Albanian-born Roman Catholic, who for those who know of her work has become a symbol of total charity and selflessness, found a calling within a calling 31 years ago.

"The message was clear. I was to leave the convent and help the poor, while living among them," Mother Teresa, 69, has said.

She exchanged her habit for a white sari with a blue border and sought out the malnourished and dying thousands in the notoriously poor Indian city, inspiring among the affluent who came to watch her work not only admiration but the question: "How can she do it?" They began to call her a living saint.

Her "pure heart" home for the dying and destitute near the Temple of Kali, the Hindu goddess of destruction, is both a harrowing scene and an extraordinary example of dedication to the lives of others.

Mother Teresa began in 1952 to help give dignity to the last days of dying people. Every morning, she and others of her order, the Missionaries of Charity, walked out among the pavement-dwellers of Calcutta and took back with them those about to die.

Many found with the Missionaries of Charity the only dignity ever offered them. The mission gave them a bath, food, clean sheets, clean clothing and a clean place to die.

"It gives me great joy and fulfillment to love and care for the poor and neglected," Mother Teresa has said. "The destitute," she said another time, are "great and lovable people."

The five-member Norwegian Nobel Committee selected Mother Teresa for the $190,000 prize from amoung 56 individuals and organizations nominated. President Carter; Soviet dissident Yuri Orlov, and South African black Steve Biko, who died after being beaton in prison, were among the nominees.

Mother Teresa has done nothing for world peace as it is discussed and analyzed by statesmen. She does not discuss nor think about world politics. "I am unworthy," Mother Teresa said in Calcutta when told of the award. "Thank God for this gift for the poor. God's blessings will be with the people who have given the prize. I hope it will be real means of bringing peace and happiness in the world of today."

She began her work alone in Calcutta in 1948. Within six months she had her first follower, an Indian nun who took the name Sister Agnes, usually Mohter Teresa's Christian name.

Mother Teresa was born Agnes Gonxha Bojaxhiu in Skopje, which is now part of Yugoslavia. Her father was an Albanian peasant-shopkeeper.

Mother Teresa said today the Missionaries of Charity have 1,800 sisters and brothers and 120,000 coworkers in 185 branches in 25 countries. In 1973, a publication described the Missionaries of Charity as the only Roman Catholic order that was growing.

By the time she was 12, Mother Teresa knew that she wanted to be a nun. She told an interviewer that the only thing that stopped her from leaving her parents then was her happy home life. When she was 17 she sailed for India with the Sisters of Loretto, an Irish order.

For 20 years, Mother Teresa taught high school in Calcutta before requesting and then fighting for permission from the Vatican to act upon her calling to help the city's poor.

"Holiness is not a luxury of the few; it is the simply duty of us all," Mother Teresa has said.

Whe was often asked, particularly in her first years, about the statistical insignificance of her work. People are still sleeping, eating, living and dying on Calcutta's streets. She has helped thousands and other thousands have remained neglected.

"Mother Teresa is fond of saying that welfare is for a purpose . . . whereas Christian love is for a person," author Malcolm Muggeridge write of her usual reply.

Where the ordinary person might shrink in horror from the dirt, disease and strangeness of Calcutta's slum dwellers, Mother Teresa sees her work as not only done for Christ, but by him.

"For me each one is an individual," she has said. "I can give my whole heart to that person for that moment in an exchange of love. It is not social work. We must love each other. It involves emotional involvement, making people feel they are wanted."

Sisters entering the order take three types of special vows before taking the final vow, the "giving of the heart." They are allowed to return to the convent to consider carefully whether they have a calling for the work.

The Nobel Peace Prize is not Mother Teresa's first award. In 1971, pope Paul VI, who had earlier called her to Rome to establish a mission for the poor there, presented her with the first Pope John XXIII Peace Prize, calling her order a symbol of brotherhood among men.

In 1964, Pope Paul visited India and gave Mother Teresa the white Lincoln Continental he traveled in for her to auction off. She sold the car without taking a ride and used the money to start a home for lepers.

Although the home for the dying and destitute is the best-known of Mother Teresa's endeavors, her order teaches children, aids lepers and other sick and provides medical care in a series of dispensaries.

Initially because of her lack of means, she was forced to turn away from the home for dying and destitute those not sick enough to die or not malnourished enough to starve.

Now the nuns, who rise at 4:40 a.m. and work until 9 p.m., with one 30-minute rest period, are able to care for many of the sick and hungry who are not near death.

Almost 15 years ago, Mother Teresa talked to a Newsweek reporter about the dying.

"Very often they are not dead when they arrive, but they are too far gone to be saved," she said. "So you have them alive and speaking, but really they are already dead. Before they die, they always ask for sweets.

"Yesterday, there was a man who lay before me and I asked him what I could give him and he said 'sweets,' which is the food of the rich. When i brought him some, he said, 'If you'd given me this yesterday, I would have eaten it, but today I cannot.' He died 10 minutes later."

Among the remarkable qualities Mother Teresa communicates is a lack of indignation. She appears to those who visit her never to despair.

Mother Teresa is firmly opposed to abortion and birth control. It strikes her as strange when a questioner asks whether there are not too many children on Calcutta's streets. The notion seems inconceivable to her.

"Without the special grace vouch-safed her, she might have been a rather hard, even grasping person," wrote Muggeridge in his book about Mother Teresa. "I never met anyone less sentimental, less scatty, more down-to-earth."

Muggeridge, like many others who traveled to the slum she has made her life's work, also said after his first encounter with her that he knew the memory of Mother Teresa would stay with him forever even if he never saw her again.