Officials have brought in extra security to avoid the near rioting that took place last year, when teenage heartthrob Robert Pattinson appeared.
Pattinson is not there, but the actors who play Alice and Emmett are, posing for pictures and signing autographs for a select number of fans who bought wristbands.
Those without wristbands will also have a chance to see actors Ashley Greene and Kellan Lutz at a public Q & A later Monday night.
Greene and Lutz also appeared on ABC7's the View from the Bay Monday afternoon. The second installment in the Twilight saga, "New Moon", opens November 20.