Damon and Affleck first became friends when their mothers introduced them. (Damon's was a professor of childhood education and Affleck's was a schoolteacher.) At the time Affleck was eight years old and Damon was ten. As the two lived a couple of blocks away from each other in Cambridge, Massachusetts, they spent plenty of time together as children and they also attended the same high school.
The pair shot to stardom with their 1997 movie Good Will Hunting, which starred Damon as the title character and featured Affleck as Will's best friend. The movie went on to receive acclaim, and the pair won an Academy Award for co-writing the movie's screenplay. In addition to this accomplishment, the two pals have consistently supported and encouraged each other over the course of their lives.
Their friendship was cemented after Affleck defended Damon in a fight
While on Conan in 2019, Damon shared that he'd once been on the verge of getting beaten up by a bigger kid. At the last second, a school-age Affleck "tackled this dude off of me. Like, out of nowhere." For Damon, Affleck hadn't only spared him from a fight, he'd cemented their friendship. "I remember that was a big moment. Like, 'This guy will put himself in a really bad spot for me. This is a good friend.'" They also came through for each other by defending their choice to pursue acting careers to parents who, given the low odds of success in the entertainment industry, were understandably worried.
Affleck began acting at a young age, as a family friend was a casting director and introduced him to the industry. But Damon helped his friend become serious about the craft. Affleck explained to Parade magazine in 2007, "Before Matt, I was by myself. Acting was a solo activity where I’d just go off and do something, act in a little TV show or something, and no one understood it. None of the other kids knew what it was I did, how it worked, or anything. All of a sudden I had this friend, Matt, and he gets it and wants to do it and thinks it's interesting and wants to talk about it. Soon both of us are doing it."
The pair held 'business lunches' in high school to plan their future
Damon has said that filmmaking became a shared pursuit for the two friends. "We were both in love with the same thing — acting and filmmaking. I think we fed on each other’s obsession during really formative, important years and that bonded us for life," Damon told ET Online. According to Damon's brother, the two were "drama geeks" in high school. During high school, they shared what they called "business lunches" to work on plans for the future, and as teens, they sometimes traveled together for auditions in New York City.
When it was time to head to college — Harvard University for Damon and, initially, the University of Vermont for Affleck — the two remained close. Affleck once explained in Interview magazine, "Matt and I had identical interests, so whether we ended up successful or making hot dogs at Dodgers games, we knew we’d end up doing the same sort of thing. The remaining friends part was pretty consistent. We saw each other all the time, we talked on the phone all the time." When they both left school to try to make it as actors, they often lived together.
A few years later, their trust and respect for one another allowed Damon and Affleck to co-write the script for Good Will Hunting, and then reap the rewards of that breakout hit.
Early on, Damon and Affleck would pool their incomes
Damon and Affleck did more than encourage each other to act — they were there for one another financially. "Ben Affleck and I actually had a joint bank account, and the bank account was money that we'd made doing local commercials and we could only use it on trips to New York to audition," Damon said on CNN in 2011. He has stated that this attitude was only natural, as their friendship had always followed those rules. "If one kid had enough for a candy bar, then the candy bar was bought and split in half — that’s just the way it’s been," he explained to Interview.
After they'd moved on from being kids shooting commercials to trying to survive on their own as struggling actors, Damon and Affleck still pooled incomes. If one got a role, that money was available to the other until the next part came in.
With the success of Good Will Hunting, they were able to put that training into practice. The two started a production company and created the reality show Project Greenlight to provide aspiring filmmakers with the opportunity to see their projects become reality.
The pair knows how to have fun through life's highs and lows
Growing up, Damon and Affleck had fun playing Little League or Dungeons and Dragons. In later years, they'd hang out in Harvard Square. When they were older, Damon has revealed they'd usually "end up at the same bar every night with the same people telling the same old jokes."
The pair also enjoyed their time as struggling actors. "Those times were fun!" Affleck told People. "We had a great time! We were young, we didn't have the kinds of fears that you have when you get into your forties if you haven't gotten to where you want to go. We were in our twenties and we just had a blast!"
And being successful Hollywood stars hasn't kept the two from indulging in the same kind of camaraderie. In a video to raise money for a charity that offered the chance for someone to go on "a best friend double date" with them, Damon teased his friend: "Ben Affleck's left eye twitches every time you say the word Gigli." This was a reference to the 2003 movie — co-starring Jennifer Lopez, whose romance with Affleck received nonstop tabloid attention — that became a notorious flop. In the same video, Affleck noted "how incredibly short Matt Damon is." In 2016, Affleck smuggled Damon onto the set of Jimmy Kimmel Live! in defiance of the humorous "feud" between Kimmel and Damon.
They still have each other's backs through life's biggest changes
Decades may have passed since they worked together on Good Will Hunting, but they continue to encourage and respect one another's work. Damon has said he'd love to be directed by his friend. However, he explained to ET Online that Affleck tends to keep his best roles close to home: "He's a brilliant director, but the problem is that he always gives the best parts to himself. So until he starts including the rest of us, I think we just have to go watch him be great in his movies."
The pair has also remained close as they made the transition from single bachelors to married family men. Affleck might've missed Damon's City Hall wedding in 2005, but he later attended his vow renewal in St. Lucia. Their families, along with Affleck's younger brother Casey, have gone skiing together. For a time, they were neighbors when Damon moved into a home on the same street as Affleck in Pacific Palisades, California.
Years later, the two still have each other's backs. In 2015, Damon spoke up for his friend in an interview with The Hollywood Reporter: "It was like he was being cast in a role, that he was a talentless kind of meathead, with his whole relationship with Jennifer Lopez. He just got cast as this person that he wasn't. It was just really painful. It was painful to be his friend, because it wasn't fair, you know? To my mind, nobody really got him at all. And through his work, he climbed from the bottom of the mountain all the way back up to the top and past where either of us had ever been."
Damon has also been there for his friend at other difficult moments, including when Affleck's marriage to Jennifer Garner fell apart. And Affleck has turned to Damon for support when he's struggled with addiction. As Affleck told Entertainment Tonight, "I can't tell you how valuable it is to have somebody who's been through things with you, ups and downs, who knows what your life experience is like, who can identify with that."