The Buffalo News reports that the event has attracted 525 players from 11 countries. It started Saturday.
Contenders will each play 31 games over five days, with winners based on number of victories and point totals.
One returning competitor is Nigel Richards, a 47-year-old Australian and resident of Malaysia who has won the past four championships.
Participants say the event is competitive but social, providing opportunities for players to bond over their shared love of the popular board game.
The tournament comes days after the announcement that 5,000 new words had been added to "The Official Scrabble Players Dictionary."
Winners will be announced Wednesday.