Catherine's birth was long expected, as her parents, Louis I of Hungary and Elizabeth of Bosnia, were childless for the first seventeen years of their marriage.Note 1 Her birth also secured the succession to the Holy Crown of Hungary, to which Catherine was heir presumptive all her life.
Being the eldest daughter of the King of Hungary and Poland who had no sons, Catherine was a much wanted bride. When she was only four years old, she was betrothed to Louis, a younger son of King Charles V of France and future Duke of Orléans. Their marriage was supposed to establish a connection between the two branches of the French royal house. Her father made a set of concessions to the Polish noblemen in exchange for recognizing Catherine (or one of her sisters) as sovereign of Poland after his death. This agreement is known as the Privilege of Koszyce.
Thus, Catherine was expected to reign over Hungary and Poland. Her father also planned to leave her his claim to the Crown of Naples and the County of Provence, which were then held by his ailing and childless cousin Joanna I. She was supposed to be married to Louis upon reaching marriageable age, and he would retain the rights to Naples even if the marriage were childless and Catherine were to predecease him, while Provence would become a hereditary fiefdom of the House of Valois. The King of France asked Catherine's father to have Catherine recognised as heir presumptive to the Holy Crown of Hungary; although Provence was important to Charles, establishing a cadet branch of the House of Valois on the Hungarian throne was also significant, as Catherine's prospect of becoming queen of Naples was not realistic.