THE FACES OF CHICAGO WERE UNKNOWN TO MANY when photographer Norman Seeff shot this L.A. session for the band’s 1978 album, Hot Streets. “All their previous covers featured graphic renditions of their logo,” he says. “No one ever saw the band.” When a “mob of guys” arrived at his studio, Seeff feared he had his work cut out for him. “When you have a large group—and a square album cover—one challenge is how to squeeze everyone in,” he explains. “It requires physical intimacy—band members nearly have to sit in each other’s laps—and sometimes you encounter some tension.” Not with this mob. “It was almost like football,” muses Seeff. “One guy would piggyback on another and run across the studio, and someone would tackle them. They were like overgrown adolescents—really fun.” The loose session with the horn-driven group yielded stunning images. “There was a kind of equity among them,” Seeff adds. “You could sense mutual respect for one another’s musicianship. They were a true ensemble.”