Harper, who'd previously written all of his own material, encouraged the band members to write as well for the album, which was recorded in seven days in Paris, following the end of an eight-week European concert tour this year.
"It was a huge shift for me creatively," Harper said, "and not one that was entirely easy to make... in that I had never done it. But it was time and I knew it was time. I could hear the music coming from each one of the (band members') corners, going, 'Man, that's great.'
"Everybody just removed their ego from the table and just brought their best musical step forward. It was scary, but I was glad I did it."
Harper and the Innocent Criminals are on the road in North America supporting the album, which came out Aug. 28.
Gal Gadot cast as Wonder Woman for 'Batman vs. Superman'
Ron Burgundy interviews Peyton Manning on SportsCenter