"One thousand happy faces, this is a one-day event where we get 1,000 people here in this place and there will be group of photographers who take pictures of every participant and all those pictures we will put together and print giant billboard," Boguslaw Szedny, said.
The billboard will then be donated to the City of Chicago and displayed on a building to make Chicago smile.
There will be music, food and drinks during the photo shoot. All of the money collected goes to Children's Memorial Hospital.
The event takes place Sunday from 4 to 10 p.m. at the Victor Hotel, 311 North Sangamon. Register online at 1000happyfaces.org. Among the celebrities on hand will be former ultimate fighter and Chicago native Shonie Carter.