Leonardo DiCaprio and Blake Lively's Romance?

Leonardo DiCaprio and Blake Lively were photographed holding hands during a stroll after dinner in Monte Carlo May 27. Us Weekly has the exclusive photos.

"He looked very in love," a witness says. DiCaprio brought her as his guest at a Grand Prix-viewing bash aboard a yacht.

"Her face lit up when Leo was talking," a fellow reveler says.

"He had introduced Blake as his girlfriend," adds a source. "I would say they're totally smitten!"

"I've never seen him like this with a girl," adds the insider of DiCaprio.