The plane had just taken off for Ottawa, Canada but returned because of smoke in the cabin and flight deck.
ABC7 is told that no one was hurt in the incident Monday.
An ExpressJet spokesperson released the following statement to ABC7: " "ExpressJet flight 5828, operating as United Express from Chicago ORD to Ottawa, Canada, declared an emergency and returned to Chicago shortly after take-off due to smoke in the cabin and flight deck. All 38 passengers deplaned safely and are in the process of being re-accommodated. We apologize for any inconvenience."