The movie documents the 2003 season of the Boston Red Sox, beginning with their annual spring training and culminating at the American League Championship Series. The documentary also looks into the team's fandom, as well as the team's interactions with their fans.
The movie's title was chosen by Red Sox fans after the documentary's director asked them to choose an appropriate title from four available choices. Other alternate titles were This Is the Year, The Ecstasy and the Agony, and Always the Bridesmaid. One of the people interviewed for the movie, a fan by the name Jessamy Finet, was later asked to perform in the 2005 film Fever Pitch based upon her role in Still, We Believe.
Critical reception was mostly positive. The Hartford Courant gave an overly positive review, but remarked that "As good as Doyle's film is, he avoids the financial issues, betraying his lack of independence from Red Sox management, whose cooperation was essential and who probably had final cut." The review from the Boston Globe was also predominantly positive, but noted that the movie covered so much material that Doyle "never goes deep enough into the season or individual games; like the sped-up overhead shots of Fenway groundskeepers that punctuate the movie, "Believe" is always rushing to the next moment."