The passports have a chart inside, containing the names of the 25 local businesses that are participating. Each store has a Waldo sticker on their door or window to show they're a part of the fun. Inside each store is a six-inch Waldo cardboard cutout hidden somewhere. The kids find the Waldo and get a stamp in their passport. Collect half of the stamps, and your child gets a Waldo pin. Collect at least 20, and your child gets entered in a drawing to win a gift basket full of Waldo books.
My kids, being competitive, got 24/25 (the last store was closed the three times we stopped by, so we ended up just turning in their passports). The fun isn't over yet, though - there's still time to pick up your passport from the bookstore and get hunting. At the end of the month, Saturday, July 29th, there will be a Waldo party and raffle drawing at 1 p.m. in the bookstore.
Good luck and have fun finding Waldo!