Director Joel Allen Schroeder began working on "Dear Mr. Watterson" in 2007, and raised nearly $100,000 for the project through Kickstarter in 2009.
"How could this strip mean so much to me when I was 10, and how could it mean so much to me when I'm 33?" Schroeder said. "And the film was born."
"Calvin and Hobbes," about an adventurous suburban 6-year-old and his "live" stuffed tiger ran from 1985 until New Year's Eve 1995, when the strip retired with the final words, "Let's go exploring!"
The strip appeared in more than 2,400 newspapers worldwide at the height of its popularity and around 45 million copies of the 18 "Calvin and Hobbes" books have been sold.
"Newspaper readership and book sales can be tracked and recorded," Schroeder writes on the film's website. "But the human impact [Watterson] has had and the value of his art are perhaps impossible to measure."
The strip's reclusive creator, Bill Watterson, lives in rural Ohio and has reportedly only given one interview since 1989. He famously refuses to license his characters for merchandizing, battling publishers who wanted to cheapen his work.
Schroeder said he didn't attempt to interview Watterson out of respect for his privacy. Instead, the documentary includes interviews with fans, cartoonists, and others who were inspired by "Calvin and Hobbes."
When asked whether Watterson had seen the finished film, Schroeder said that he had, and that he appreciated Schroeder's commitment to respecting his privacy.