William meets another boy in his school who has the same name and roughly the same appearance, and who was even born on the same date (January 19, Poe's own birthday). William's name (he asserts that his actual name is only similar to "William Wilson") embarrasses him because it sounds "plebeian" or common, and he is irked that he must hear the name twice as much on account of the other William.

The boy also dresses like William, walks like him, but can only speak in a whisper. He begins to give advice to William of an unspecified nature, which he refuses to obey, resenting the boy's "arrogance". One night he steals into the other William's bedroom and recoils in horror at the boy's face—which now resembles his own. William then immediately leaves the academy and, in the same week, the other boy follows suit.