Elephant was shot in Portland, Oregon, where Van Sant lives. By the time pre-production was to get underway, Van Sant had made the critically acclaimed Gerry, working with a minimal script and in close collaboration with actors Matt Damon and Casey Affleck and a small crew that included producer Wolf, director of photography Harris Savides and sound designer Leslie Shatz. Says Wolf, "We had such a good experience with Gerry that Gus decided to work that way again, with a loose script and an improvisational approach."

The process began with casting, and the decision was made to seek out actual high school students for the film’s student roles, including extras. An open casting call was held in Portland, and drew some 3,000 teenagers. Recalls Wolf, "The local casting director, Danny Stoltz, did a great job with flyers and radio ads – and then because it was Gus, the local TV stations picked it up, and it just became this huge scene. It was pretty phenomenal. Gus wandered around, meeting kids and talking to them."

Eventually the applicants were winnowed down to smaller groups. Award-winning casting director Mali Finn met with students and talked with them about their lives. The subject of school shootings was approached very directly, reports Van Sant. "Mali is really great at getting people in a certain space where they start talking about their lives. We would ask things like ‘Do you feel safe in school? Does this happen? What happens in your life?’" he remembers. "These kids are steeped in being conscious about all the school shootings, because they’re in school. So I think there’s a certain amount of anxiety and there’s a certain amount of opinion. And they are smart. For some of them it’s very hard to be in school, it’s like hell. Sometimes they use that word, ‘hell.’ For others, school is great. I think there was a similar disparity when I went to high school."

Students were encouraged to shape their parts from their own lives, integrating their own stories and experiences. There were no scripted lines, and students essentially improvised their dialogue, though sometimes Van Sant suggested that they revisit a story or a conversation he’d heard from them before. "People were part of the process of creating their characters. Most of the kids are playing, very loosely, roles that they would be in real life," he remarks. The exceptions to that general rule are Alex Frost and Eric Deulen, who were cast as the two boys that bring the day to a sudden close. Out of the entire cast, there are only three professional actors, all in adult roles: Timothy Bottoms as the father of one student, Matt Malloy as the school’s principal, Mr. Luce, and Ellis E. Williams as the leader of the Gay Straight Alliance.

Keaton, an Academy Award® winner for her performance in Annie Hall, applauds Van Sant’s decision to continue the improvisational techniques he had explored in Gerry. "I think it’s a fascinating way to go. It’s astonishing what can happen with actors when they’re guided by somebody with the gifts, the skill, and the insight that Gus has," she comments. "Also, Gus has an incredible knack for spotting talent. The kids trusted him, and they just did it – and did it effortlessly."