Cardinal Sarah, who had been president of the Pontifical Council Cor Unum, the Vatican's charitable distribution and promotion office, since 2010, succeeds Cardinal Antonio Canizares Llovera, who was named archbishop of Valencia, Spain, in August.
The Vatican announced Cardinal Sarah's appointment Nov. 24 as the pope was meeting him and the other presidents of pontifical councils and prefects of Vatican congregations.
Jesuit Father Federico Lombardi, Vatican spokesman, said the meeting was one of the gatherings Pope Francis holds with the heads of Vatican offices every six months. However, in view of the planned reorganization of the Roman Curia, the meeting also was an opportunity to explain the ideas developed so far by Pope Francis' nine-member Council of Cardinals.
"It was useful to have this meeting to collect opinions" before the Dec. 9-11 meeting of the council, which Pope Francis named to advise him on the Curia reform and on the governance of the church in general, Father Lombardi said.
The spokesman told reporters he understood that the process of making decisions and fine-tuning ideas about how to reorganize the Vatican offices "would continue for several months still. There is no sense that a new constitution is imminent."
Cardinal Sarah takes up the reins at the worship congregation after four years spearheading retired Pope Benedict XVI's attempts to ensure that Catholic aid and charitable activity include not only material assistance, but also spiritual care for the poor, refugees and victims of natural disasters.
He was appointed head of Cor Unum after nine years serving as secretary of the Congregation for the Evangelization of Peoples, which oversees and cares for Catholic dioceses and jurisdictions in missionary territories.
Cardinal Sarah came to the Vatican after serving for 21 years as archbishop of Conakry, Guinea. His time in the archdiocese included the last five years of the ruthless Marxist dictatorship of Ahmed Sekou Toure, who died in office in 1984. The then-Archbishop Sarah earned a reputation as one of the few voices courageous enough to defend freedom and promote human dignity.
In a 2012 speech to the Synod of Bishops on the new evangelization, Cardinal Sarah insisted the Catholic Church is not a social service agency; its aim is always and everywhere to lead people to the God who is love, and that is done through concretely demonstrating that love.
While the church never ties its offers of help to promises of conversion, the cardinal said, many people have come to faith in Christ and joined the church because of the love they experienced through Catholic charity.
Missionary activity and charity -- in the form of education, health care, sanitation, development aid and the defense of human rights -- always have gone hand in hand, he told the synod.
At the 2009 special Synod of Bishops for Africa, then-Archbishop Sarah said, "Africa must protect itself from the contamination" of increasingly popular Western ideas about family life and sexuality.
"In African culture," he said, "man is nothing without woman and woman is nothing without man. Both are nothing if the child isn't the center of the family created by a man and a woman and the base of society."
Attempts to redefine the family, to accept homosexual activity and to promote abortion as a right undermine the very fabric of stable societies, he said: "There is no peace, no justice, no stability in society without family, without cooperation between man and woman, without a father and without a mother."
Born June 15, 1945, in Ourous, Guinea, he was educated in seminaries in the Ivory Coast and Guinea. He earned a licentiate degree in theology from the Pontifical Gregorian University in Rome and another licentiate in Scripture from the Studium Biblicum Franciscanum in Jerusalem.
He was ordained to the priesthood in 1969 and served as rector of the minor seminary in Kindia, Guinea, as well as pastor at several local parishes. When he was consecrated a bishop at the age of 34 he was the youngest bishop in the world. He served as archbishop of Conakry from 1979 to 2001.