Both have been around for four decades and hail from Chicago.
And, both legendary acts made a special stop on the deck of the Intrepid Sea, Air & Space Museum for The Early Show's Summer Concert Series Friday.
The bands have certainly seen their share of success over the years. Earth, Wind & Fire, formed in 1969, has sold more than 90 million albums worldwide. And Chicago, brought together in 1967, has had 25 albums go platinum.
The bands continued that success by touring together in 2004 and 2005.
But now, they're teaming again, not just to tour, but to share the stage and play their songs together. Their co-headlining 30-city summer tour is a dream double bill -- one fans have been asking for since the last time they were together.
Lee Loughnane, who plays trumpet for Chicago, said, "They're more R&B and we're more rock 'n' roll, and it blends very nicely."
"It's fun to play the other act's songs," said Phillip Bailey, of Earth, Wind & Fire, "and it's just big."
Robert Lamm, of Chicago, said with the brass section "beefed up" and "double strength," the sound of some songs is changed.
But what's it like for these two iconic bands to tour together?
Verdine White, of Earth, Wind & Fire, said the camaraderie between the bands is good. "And everyone is joking around on and off the stage," he said.
Earth, Wind & Fire found a stage this year in an unlikely place: The White House. The group's members say they were surprised when President Obama revealed the group was one of his favorites -- and asked them to play at his new home on Pennsylvania Avenue.
EWF drummer Ralph Johnson said, "It was an incredible moment, and he's so down-to-earth."
White called the experience "over the top."
But what's kept the bands going so long?
Chicago says its fans and their reaction to their music have sustained them for the more than 40 years they've been together.
Walter Parazaider, of Chicago said, "You have to be a very depressed person to not enjoy people going 'yeah!"'