Hundreds of Catholic nuns and slum dwellers in the Indian city of Calcutta have marked the 100th anniversary of the birth of Mother Teresa.
A special Mass was held at the headquarters of the Missionaries of Charity - the order of nuns which Mother Teresa founded 60 years ago.
Mother Teresa, an ethnic Albanian, was born in Skopje, now part of Macedonia, on 26 August 1910.
Her work in the Calcutta slums earned her a Nobel peace prize in 1979.
The doors of Mother House in Calcutta were opened at dawn and hundreds of slum dwellers from the city walked in to light candles and pray at her tomb.
A message from Pope Benedict XVI was read out at the Mass.
"I am confident that this year will be for the Church and the world an occasion of joyful gratitude to God for the inestimable gift that Mother Teresa was in her lifetime and continues to be through the affectionate and tireless work of you, her spiritual children," the message said.
"Her life and work continue to be an inspiration for young and old, rich and poor from all walks of life, religions and nations," the current head of Missionaries of Charity, Sister Prema, said.
As Agnes Gonxha Bojaxhiu, she arrived in India as a novice in 1929 and dedicated herself to working among the sick, dying and destitute.
She took the name of Teresa on taking her vows as a nun in 1931 and in 1950 established the order which runs homes for abandoned children, the elderly and those suffering from leprosy and Aids.
She was known as the "Saint of the Gutters" for her work among the poor of Calcutta.
After her death in September 1997, she was buried at the headquarters of the Missionaries of Charity, which is now a pilgrimage site.
She was beatified - the first stage in becoming a saint - in 2003 by Pope John Paul II. It was done in record time in the modern era.
Mother Teresa's beatification has now paved the way for her canonisation, which many expect will happen soon.