Michelle Williams: Blue Valentine fulfilled lifelong dream
The film, which was released back in January in the UK, also starred Ryan Gosling and John Doman.
It told the story of a married couple and their relationship over their years together.
Speaking to NPR's Fresh Air, the actress said she was able to improvise during the film, adding that they only had one chance to get it right with each scene.
"It felt like such a rare opportunity and one that... I know I'll probably never have again. I have dreamed [of] working [that way] since I was a kid because it was such a throwback," she said.
Williams, who was nominated for an Oscar for her role in the film, adding that being able to experiment like that in a film fulfilled a "long-time desire" she had.
The actress, who rose to fame playing Jen Lindley in Dawson's Creek, will next be seen in My Week with Marilyn.