It's a warm summer night. You’ve managed to score a coveted ticket to the Jonas Brothers concert, where you’re singing at the top of your lungs about scorching temperatures, outselling Kelly Clarkson ...

During their concert in Virginia Beach, Va. on Friday, Aug. 15, Nick Jonas, Joe Jonas and Kevin Jonas brought out Hanson, ...

From Jesse McCartney to Demi Lovato, here's who the Jonas Brothers have surprised fans with on their Jonas20 Tour, so far.