Pratyush Buddiga, 13, survived 11 rounds, outlasting 249 other contestants who began the competition Wednesday. He takes home an engraved trophy and $12,000.
"I didn't think I really had a chance to win," he said. "I just wanted to be in the top five."
The first public school student to win the competition since 1999, Pratyush attends Mountain Ridge Middle School in Colorado Springs. His family hails from India, but Pratyush was born in New Zealand and they came to the United States in 1995.
A first-time competitor in the national bee, he went head-to-head in the final rounds with Steven Nalley, 14, of Starkville, Miss. Steven was returning for his second try at the championship.
Ninety spellers began the day onstage, having survived an unprecedented 25-word written test Wednesday.
In the final day of competition, contestants successfully worked their way through "kakemono," "caulicolous," "stultiloquence," "culgee," "hermeneutics," "soavemente" and "toreutics," among others.
The final rounds featured sudden exits by several contestants who seemed virtually invincible.
The capacity crowd gasped when Michael Hessenauer, 14, of Dublin, Ohio, bowed out in Round 5, missing "verticil," describing a circle of similar parts, as with flowers or hairs. Michael was the highest ranked speller returning from the 2001 competition. He tied for third last year, and was in the finals for the third time.
Erik M. Bolt, 14, of South Bend, Ind., one of two finalists making their fourth trip to the competition, was among the final nine contestants. He was eliminated in Round 7 on "badigeon," a cement used to cover holes in wood or stone.
Also eliminated was Mallika Thampy of St. Louis, little sister of the 2000 champ. She tripped up on "batture," a French word meaning the land between a low river and a levee.
Emily Cole, 14, of Boiceville, N.Y., another speller making her fourth trip to the bee, correctly spelled "pugilist," a boxer, on Wednesday, but was eliminated in the written test.
Other finalists stumbled on these tough nuts: "throstle," "roriferous," "tiralee," "objicient" and "icteric," among others.
Thursday's finals were broadcast live on ESPN, the cable sports network. First lady Laura Bush opened the broadcast with taped comments, telling the contestants, "I am very proud of you. I hope you'll always work hard at spelling and at reading. The more you read, the better your spelling will become and the more your vocabulary will grow."
Among the guests of honor watching the competition Thursday was Frank Neuhauser, 88, winner of the first National Spelling Bee in 1925.
After he won, Neuhauser got to shake hands with Calvin Coolidge, then received a hero's welcome in his hometown of Louisville, Ky.
After sitting through one round Thursday, Neuhauser said, "The words are, in my judgment, much more difficult."