Born in Carpineto Romano, near Rome, he was the sixth of the seven sons of Count Ludovico Pecci and his wife, Anna Prosperi Buzzi.
His brothers included Giuseppe and Giovanni Battista Pecci.
Until 1818, he lived at home with his family "in which religion counted as the highest grace on earth, as through her, salvation can be earned for all eternity."
Together with Giuseppe, he studied in the Jesuit College in Viterbo, where he stayed until 1824.
He enjoyed Latin and was known to write his own Latin poems at the age of eleven.

In 1824, he and Giuseppe were called to Rome, where their mother was dying.
Count Pecci wanted his children near him after the loss of his wife and so they stayed with him in Rome and attended the Jesuit Collegium Romanum.

In 1828, the 18-year-old Vincenzo decided in favour of secular clergy, and Giuseppe entered the Jesuit order.
Vincenzo studied at the Academia dei Nobili, mainly diplomacy and law.
In 1834, he gave a student presentation, attended by several cardinals, on papal judgments.
For his presentation, he received awards for academic excellence and gained the attention of Vatican officials.
Cardinal Secretary of State Luigi Lambruschini introduced him to Vatican congregations.
During a cholera epidemic in Rome, he assisted Cardinal Sala in his duties as overseer of all the city hospitals.
In 1836, he received his doctorate in theology and doctorates of civil and Canon Law in Rome.
Born in Carpineto Romano, near Rome, he was the sixth of the seven sons of Count Ludovico Pecci and his wife, Anna Prosperi Buzzi. His brothers included Giuseppe and Giovanni Battista Pecci. Until 1818, he lived at home with his family "in which religion counted as the highest grace on earth, as through her, salvation can be earned for all eternity." Together with Giuseppe, he studied in the Jesuit College in Viterbo, where he stayed until 1824. He enjoyed Latin and was known to write his own Latin poems at the age of eleven.
In 1824, he and Giuseppe were called to Rome, where their mother was dying. Count Pecci wanted his children near him after the loss of his wife and so they stayed with him in Rome and attended the Jesuit Collegium Romanum.
In 1828, the 18-year-old Vincenzo decided in favour of secular clergy, and Giuseppe entered the Jesuit order. Vincenzo studied at the Academia dei Nobili, mainly diplomacy and law. In 1834, he gave a student presentation, attended by several cardinals, on papal judgments. For his presentation, he received awards for academic excellence and gained the attention of Vatican officials. Cardinal Secretary of State Luigi Lambruschini introduced him to Vatican congregations. During a cholera epidemic in Rome, he assisted Cardinal Sala in his duties as overseer of all the city hospitals. In 1836, he received his doctorate in theology and doctorates of civil and Canon Law in Rome.
Pope Leo XIII