Affleck began acting at age 5, going to auditions with big brother Ben. “We would get to be an extra,” he recalls of those first movie gigs. “You can find us in ‘Field of Dreams,’ in ‘The Good Mother,’ me in it more prominently. We’d get 20 bucks, get to eat donuts all day.”

Then at 18, “right out of high school,” the younger Affleck did “To Die For,” the first of his three films with Gus Van Sant. He lived in Los Angeles, auditioned, “but I couldn’t get any traction,” he says.

So he took a break for college and then came back when his brother, only three years older, moved to the Hollywood A-list and won an Oscar. The younger Affleck denies there was ever any competition between the two brothers. “Really, what is the point?” he says. “You get to where you have had enough failures and you realize that you’ve got one brother. You are going to ruin the relationship by being competitive over who gets to be in a movie? Are you kidding me?”

In “The Assassination of Jesse James by the Coward Robert Ford,” Casey Affleck resembles a modern-day celebrity stalker. In his brother’s “Gone Baby Gone,” he’s a detective hired for a missing-child case. It’s a role he was offered while acting in the Brad Pitt starrer. Not that he immediately snapped up his brother’s sales pitch: “I said I would read the script and I would love to work with him, but I wanted to make sure that I was right for it. I didn’t want to screw it up. I know that casting is so important in directing a first movie, and a lot is at stake. If you don’t pull it off the first time, then you rarely get a second shot. So I wanted to be very careful about the decision. We talked a lot, we disagreed about everything, and then I said, ‘I’m in.'”