Why is Kate a princess?
Kate Middleton will become a princess when she marries Prince William. If William becomes king, Kate would then become queen. If Queen Elizabeth II abdicates the throne to Prince Harry however, Kate will remain a princess. This would seem unlikely considering William is in line to the throne before Harry.
Titles Given by Queen Elizabeth: Shortly before their wedding, Queen Elizabeth released the titles William and Kate will be known by. Kate's first title will be Duchess of Cambridge, her second title is Countess of Strathearn, and her third title is Baroness Carrickfergus. Previous answer: Her Royal Highness Princess William of Wales After her marriage to Prince William of Wales, Kate Middleton's title will be Her Royal Highness Princess William of Wales. On the engagement…
Because she had no title before her marriage to Prince William she is not Princess in her own right. She can be refered to as Princess William though. That is why people have been refering to the couple as Duke and Duchess of Cambridge and not Prince William and Princess Catherine-because technically she is not Princess Catherine.