Early life (1509–1535)
Calvin was originally interested in the priesthood, but he changed course to study law in
. Painting titled Portrait of Young John Calvin
from the collection of the Library of Geneva.
John Calvin was born as Jehan Cauvin on 10 July 1509, at
Noyon, a town in
Picardy, a province of the
Kingdom of France.
 He was the first of four sons who survived infancy. His mother, Jeanne le Franc, was the daughter of an innkeeper from
Cambrai. She died of an unknown cause in Calvin's childhood, after having borne four more children. Calvin's father,
Gérard Cauvin, had a prosperous career as the cathedral
notary and registrar to the
ecclesiastical court; he died in 1531, after suffering for two years with testicular cancer. Gérard intended his three sons — Charles, Jean, and Antoine — for the priesthood. The surname Calvin or Cauvin is in origin a diminutive of French chauve (Picard calve, from Latin
calvus) meaning "bald".
Young Calvin was particularly precocious. By age 12, he was employed by the bishop as a clerk and received the
tonsure, cutting his hair to symbolise his dedication to the Church. He also won the patronage of an influential family, the Montmors.
 Through their assistance, Calvin was able to attend the
Collège de la Marche ,
Paris, where he learned
Latin from one of its greatest teachers,
 Once he completed the course, he entered the
Collège de Montaigu as a philosophy student.
In 1525 or 1526, Gérard withdrew his son from the Collège de Montaigu and enrolled him in the
University of Orléans to study law. According to contemporary biographers
Theodore Beza and
Nicolas Colladon, Gérard believed that Calvin would earn more money as a lawyer than as a priest.
 After a few years of quiet study, Calvin entered the
University of Bourges in 1529. He was intrigued by
Andreas Alciati, a humanist lawyer. Humanism was a European intellectual movement which stressed classical studies. During his 18-month stay in
Bourges, Calvin learned
Koine Greek, a necessity for studying the
Alternate theories have been suggested regarding the date of Calvin's
religious conversion. Some have placed the date of his conversion around 1533, shortly before he resigned his chaplaincy. In this view, his resignation is the direct evidence for his conversion to the evangelical faith. However, T. H. L. Parker argues that while this date is a terminus for his conversion, the more likely date is in late 1529 or early 1530.
 The main evidence for his conversion is contained in two significantly different accounts of his conversion. In the first, found in his Commentary on the Book of Psalms, Calvin portrayed his conversion as a sudden change of mind, brought about by God:
God by a sudden conversion subdued and brought my mind to a teachable frame, which was more hardened in such matters than might have been expected from one at my early period of life. Having thus received some taste and knowledge of true godliness, I was immediately inflamed with so intense a desire to make progress therein, that although I did not altogether leave off other studies, yet I pursued them with less ardour.
In the second account, Calvin wrote of a long process of inner turmoil, followed by spiritual and psychological anguish:
Being exceedingly alarmed at the misery into which I had fallen, and much more at that which threatened me in view of eternal death, I, duty bound, made it my first business to betake myself to your way, condemning my past life, not without groans and tears. And now, O Lord, what remains to a wretch like me, but instead of defence, earnestly to supplicate you not to judge that fearful abandonment of your Word according to its deserts, from which in your wondrous goodness you have at last delivered me.
Scholars have argued about the precise interpretation of these accounts, but most agree that his conversion corresponded with his break from the Roman Catholic Church.
 The Calvin biographer
Bruce Gordon has stressed that "the two accounts are not antithetical, revealing some inconsistency in Calvin's memory, but rather [are] two different ways of expressing the same reality."
By 1532, Calvin received his
licentiate in law and published his first book, a commentary on
De Clementia. After uneventful trips to Orléans and his hometown of Noyon, Calvin returned to Paris in October 1533. During this time, tensions rose at the
Collège Royal (later to become the Collège de France) between the humanists/reformers and the conservative senior faculty members. One of the reformers,
Nicolas Cop, was rector of the university. On 1 November 1533 he devoted his inaugural address to the need for reform and renewal in the Roman Catholic Church.
The address provoked a strong reaction from the faculty, who denounced it as heretical, forcing Cop to flee to
Basel. Calvin, a close friend of Cop, was implicated in the offence, and for the next year he was forced into hiding. He remained on the move, sheltering with his friend Louis du Tillet in
Angoulême and taking refuge in Noyon and Orléans. He was finally forced to flee France during the
Affair of the Placards in mid-October 1534. In that incident, unknown reformers had posted placards in various cities criticizing the Roman Catholic
mass, to which adherents of the Roman Catholic church responded with violence against the would-be Reformers and their sympathizers. In January 1535, Calvin joined Cop in Basel, a city under the influence of the reformer