Francis de Sales was born on 21 August 1567 in the Château de Sales into the noble Sales family of the Duchy of Savoy, in what is today Thorens-Glières, Haute-Savoie, France. His father was François de Sales, Lord of Boisy, Sales, and Novel. His mother was Françoise de Sionnaz, the only child of prominent magistrate, Melchior de Sionnaz, and a noblewoman. He was baptized Francis Bonaventura, after two great Franciscan saints. His father wanted him, the first of his six sons, to attend the best schools in preparation for a career as a magistrate. He therefore enjoyed a privileged education in the nearby town of La Roche-sur-Foron and at the age of eight, at the Capuchin college in Annecy.
In 1583, De Sales went to the Collège de Clermont (later renamed Lycée Louis-le-Grand) in Paris, then a Jesuit institution, to study rhetoric and humanities. As a nobleman, he was accompanied by his own servant and by a priest tutor, Abbe Deage. To please his father, he took lessons in the gentlemanly pursuits of riding, dancing, and fencing. De Sales is described as intelligent and handsome, tall and well built with blue-grey eyes, somewhat reserved and quiet, and a welcome guest in the homes of the nobility among whom his father had connections.
In 1584 Francis de Sales attended a theological discussion about predestination, convincing him of his damnation to hell. A personal crisis of despair resulted. This conviction lasted through December 1586. His great despair made him physically ill and even bedridden for a time. Sometime in either late December or early January 1587, with great difficulty, he visited the old parish of Saint-Étienne-des-Grès, Paris, where he prayed the "Memorare" before a famed statue of Our Lady of Good Deliverance, a Black Madonna. He consecrated himself to the Blessed Virgin Mary, and decided to dedicate his life to God with a vow of chastity. He then became a tertiary of the Minim Order.
Sales ultimately concluded that God had good in store for him, because "God is love", as John's First Epistle attests. This faithful devotion to the God of love not only expelled his doubts but also influenced the rest of his life and his teachings. His way of teaching Catholic spirituality is often referred to as the Way of Divine Love, or the Devout Life, taken from a book he wrote of a similar name: Introduction to the Devout Life.
In 1588 Sales completed his studies at Collège de Clermont and enrolled at the University of Padua in Italy, where he studied both law and theology. He took Antonio Possevino, a priest in Society of Jesus, as his spiritual director. There he made up his mind about becoming a priest. In one incident, he rode a horse, and his sword fell to the ground and crossed another sword, making the sign of the Christian cross.