From the official rules:

Eligibility: The National Vocabulary Championship ("NVC") is open to legal residents of the 50 United States and the District of Columbia (excluding Guam, Puerto Rico and all other U.S. territories and possessions) who reside and are physically located in the United States or D.C. at the time of entry, and who are in grades 9, 10, 11 or 12, and between the ages of 13 and 19 on the date of each applicable NVC exam and/or event.

Well, that disqualifies me, my two children and my grandson. I do have a couple of nieces and nephews that fall in the age range, though.