Patricia Arquette, best known to general audiences for playing Allison Dubois on the TV series Medium, is 46 years old. Ellar Coltrane who, its safe to say, is an unknown actor, is 19. In Richard Linklaters new movie Boyhood, Arquette plays the well-meaning but constantly struggling Olivia, and Coltrane plays her son Mason. When Linklater started filming, Arquette was 34, and Coltrane was 7. Both knew, as did every other actor involved, that Linklaters plan was to shoot the dramatic, scripted film, a few days every year, for 12 years, to present a fictional picture of Masons boyhood.

Stopping in Boston last week as part of a publicity tour for the film, Arquette and Coltrane spoke about the incredibly ambitious, one-of-a-kind project that also happens to be an engrossing and entertaining movie.

Rick [Linklater] knew that I was a mom at 20, said Arquette, and maybe that was in the back of his mind when he first called me. He said, What are you gonna be doing the next 12 years? I didnt think he could be referring to a movie, but then he said he was thinking about shooting this movie over 12 years. He said he didnt have a script yet, but he did tell me the major plot points of the family.

Coltrane remembers going to a few auditions and talking to Linklater.

He didnt have a script yet for me to read, so it was just kind of a conversation, he said.He explained the concept, and he was always upfront that it was going to take a long time.

Arquette was immediately excited about it, and signed on without much deliberation. Coltrane was also excited, but he was only 7, so his parents were really the ones making the decision.

But they have a great way of just kind of supporting me and whatever Im interested in, he said. Theyre both artists, and at one time were both very involved in performance art and music and visual arts.

And, he added, they were big fans of Rick, whose directing resum includes Dazed and Confused as well as the Sunrise-Sunset-Midnight trilogy that starred Julie Delpy and Ethan Hawke, who plays Masons dad in Boyhood.

Although the endeavor was spread out over 12 years, with the story peeking in on specific events in the characters lives, actual filming only took 39 days. But it was no easy task getting things together each year.

Whenever Id be working on something or trying to plan a family vacation, the first thing I thought was call Boyhood and ask what dates theyre thinking of, said Arquette. Then I would go to my producers on Medium and ask for a four-day weekend. Sometimes we were all working on other projects and we would have to find a weekend to shoot on.

There would also be a lot of advance preparation for the yearly shoots, but not in a way any of the actors had been involved with before.

It was sort of an open structure, said Arquette. Rick would call and say, In a few months were gonna be shooting the next year, so start thinking about this. Then, for example, hed say to me, Youll have a scene with the kids, and youre all gonna be moving, but the kids dont want to move. Then right before we would come to shoot, he would give us a rough draft of the scene, written out. Wed come in, read that draft, wed talk about our own life experiences, people we knew, what our kids said when we had moved, what we said to our parents. Everyone would contribute their real-life stories. Then we would improvise the scene, and Rick would then take parts of improvisation pieces of peoples real lives, and pepper them into the written script, then rewrite it. But there wasnt a lot of improvisation on the set.

Coltranes character Mason has an older sister named Samantha in the film, played by Linklaters daughter Lorelei. The veteran actors, Arquette and Hawke, tried to make things easier for their young costars.

It was always a learning experience, said Coltrane, and it wasnt ever difficult. When I was young, it was more of Patricia and Ethan trying to make me and Lorelei more comfortable, and not feel pressured or overly self conscious. But as we got older I became very much a part of that process. Rick and I talked a lot as the years went on, and both myself and Lorelei became more invested in it, became more confident, and were able to put more of ourselves into the script.

While neither Arquette nor Coltrane could recall what happened during their first day on the set, their last days there will be with them for a long time.

I love to end movies, I love to be done with projects, said Arquette. But on this one, the whole last year I was really sad. I didnt want it to end. It was just an incredible experience for me artistically and as a human being. I was freaked out about this ending.

The last moment in the film is the last moment we shot, said Coltrane. That moment that Mason is experiencing on camera, where hes reaching a turning point in his life, and struggling to appreciate the moment of where he is ... I was coming to the end of this project that had been my entire recallable life, and was very much taken aback by that. I was trying to appreciate that moment. It was very bittersweet.

Ed Symkus covers movies for More Content Now.