Pope John Paul II presided over the open air Mass but, for the first time in a major Vatican ceremony, was unable to utter a word of his homily, leaving other prelates to do so. In the few prayers he did say, his words were so slurred and shaky they could barely be understood.
John Paul did declare Mother Teresa "blessed," moving the woman many called a living saint for her work in the slums of Calcutta one step closer to official sainthood - and bestowing the honor during his 25th anniversary celebrations.
The honor is felt perhaps most strongly in Calcutta, in the convents of the Missionaries of Charity, the order of nuns founded by Mother Teresa.
"The beatification gives us new vigor and zeal because Mother Teresa has been held up as a model of holiness by the Roman Catholic Church," said Sister Christie, a Missionaries of Charity nun in Calcutta. "With the official recognition, more people will be eager to follow in Mother Teresa's footsteps."
The ceremony in Vatican City Sunday followed a particularly grueling week for the ailing 83-year-old pope, who celebrated his anniversary Mass on Thursday while gearing up for another lengthy ceremony Tuesday to install 30 new cardinals.
Sunday's crowd was estimated at 250,000 - one of the largest ever at the Vatican - and the ceremony was a colorful mix of Indian dance and sitar music with traditional Catholic hymns, reflecting the cultures in which Mother Teresa lived and worked.
"In her, we perceive the urgency to put oneself in a state of service, especially for the poorest and most forgotten, the last of the last," John Paul said at the start of the service, held on a sunny Roman morning.
St. Peter's Square and the streets feeding into it overflowed with pilgrims, tourists and nuns of Mother Teresa's Missionaries of Charity order, grouped in small clusters of their trademark indigo-trimmed white saris alongside cardinals in scarlet cassocks and politicians in somber black.
In her lifetime, Mother Teresa was often called the Saint of the Gutters, because of her work among the poor.
"We considered her a saint for a long time. So it wasn't this sudden awareness to say, gee, Mother Teresa died now we can talk about her as a saint," said Monsignor Paul Robichaud, a Church scholar, in a CBS News interview. "She been talked about in those terms for a very, very long time."
While most pilgrims don't consider Mother Teresa's new official status surprising, many were overwhelmed by the papal recognition.
Some nuns wept, and others buried their heads in their hands when the smiling, wrinkled face of Mother Teresa was unveiled on a tapestry hanging from the facade of St. Peter's Basilica.
John Paul himself appeared greatly affected as Indian girls bearing blue and white flowers performed an offertory Indian dance and accompanied a wooden reliquary containing a sample of Mother Teresa's blood to the altar.
Beatification allows public veneration for holy people, so the relic - blood on a piece of cotton inside the reliquary - can go on display.
In the reserved seats closest to the altar sat representatives from 27 official delegations, including the presidents of Albania, Macedonia and Kosovo, Belgian Queen Fabiola and royalty from Liechtenstein, Romania and Jordan.
Also attending were Muslim and Orthodox Christian delegations from Albania, whose government declared a national holiday. Mother Teresa was born to an ethnic Albania family in the Macedonian capital, Skopje.
Sitting among them were about 2,000 homeless men and women who eat and sleep in soup kitchens and shelters run by Mother Teresa's followers. They were invited to a special luncheon inside a Vatican hall after the ceremony.
"She gave me hope," said Mara Moarem, a 55-year-old Albanian immigrant who lives at Casa Serena, a Roman shelter run by the Missionaries of Charity. "I am Albanian, she was Albanian. She is my countrywoman," he said before the lunch of lasagna, chicken, peas and bananas.
Also on hand was Monica Besra, an Indian woman who the Vatican says was cured of a medically incurable abdominal tumor after praying to Mother Teresa - the miracle it needed for beatification. Besra and her family embraced Catholicism after she recovered.
"I was so sick, Mother prayed for me," she said a few days before the ceremony. "For that reason I became Catholic. This is my faith."
The ceremony was broadcast live to Missionaries of Charity orphanages and leprosy homes in India, where Mother Teresa founded her order. A special Mass was held at the modest building on a narrow Calcutta lane where Mother Teresa lived for most of her life and now houses her mission's headquarters. Dozens of nuns led the singing of hymns and prayers.
Born Agnes Gonxhe Bojaxhiu in 1910, Mother Teresa founded the Missionaries of Charity order in 1949, after what she called an inspiration from God to care for the world's most destitute and sick. With 703 houses in 132 countries, the religious order is considered to be the fastest growing in the Catholic Church.
Critics have taken issue with Mother Teresa's faith-based advocacy against abortion and condoms in such an overpopulated and AIDS-stricken country as India, while others have faulted her for having accepted donations from dictators.
As her beatification neared, some in India protested the Vatican's claim of Besra's cure, saying talk of miracles insulted the saintly work Mother Teresa did every day and could encourage the poor to seek out religious gurus and quacks rather than going to doctors.
John Paul waived the normal five-year waiting period for the beatification process to begin and launched it a year after Mother Teresa's 1997 death, convinced of her saintliness and apparently intent on at least beatifying her in his lifetime.
The Rev. Brian Kolodiejchuk, the postulator or chief advocate for the beatification, said that by setting a Vatican record for beatification, John Paul was showing more than just his personal admiration for the tiny, stooped nun.
His desire to make her a new model for Catholics was "in some way to present Mother Teresa as one very prominent example of someone who in many respects lived some of the things he's been teaching in his pontificate," Kolodiejchuk said.
With Sunday's ceremony, John Paul has beatified 1,315 people and canonized 476 - far more than his predecessors of the past 500 years combined. Mother Teresa needs a second miracle to be made a saint.
The pope's inability to deliver his homily Sunday was another sign of the toll taken by Parkinson's disease, which has robbed him of the ability to speak clearly and compounded other ailments that prevent him from walking or standing.
Despite speculation he might step down, he has insisted on pressing head, telling cardinals Saturday he would serve "as long as the Lord wishes."