What is the correct way to address a Princess?

United States
February 4, 2007 12:43pm CST
When writting a letter to a Princess, what would be the correct way to address her?
2 responses
@hariharbhat (1312)
• India
5 Feb 07
Lovely Princess of the Prince, Greetings.
• Philippines
4 Feb 07
Your Highness or Your Royal Highness