There are two source materials that can be used for adjudication.
Prior to beginning a game, the two players decide which source will be used for adjudication. Either
1. The Official Scrabble Players Dictionary,
Fourth Edition. This dictionary has the "naughty" words expunged. This dictionary has the red cover.
2. Official Tournament and Club Word List,
Second Edition. If you choose to play by this source, you can either use the book or the computer for adjudication.
ALSO SEE CHALLENGES.