The album's title was influenced by Furtado's parents' immigration to Canada, "When I look at my old photo albums, I see pictures of their brand-new house, their shiny new car, their first experiences going to very North American-type places like Kmart. When you have that in your blood, you never really part with it—it becomes your own personal folklore." The album also displayed a diverse sound but with a more rock-oriented, acoustic approach. Furtado attributed the mellowness of the album to the fact that she was pregnant during most of its recording. "Saturdays" features vocals by Jarvis Church and "Island of Wonder" features vocals by Caetano Veloso.
Folklore includes the single "Força" (meaning "carry on" or "strength" in Portuguese), which was written as the official anthem of the 2004 European Football Championship. Furtado performed the song at the championship's final in Lisbon, in July 2004. Other singles included the ballad "Try" and "Powerless (Say What You Want)", in which she embraces her Portuguese heritage; the song deals with "the idea that you can still feel like a minority inside, even if you don't look like one on the outside". Additional singles were released in certain territories; "Explode" in Canada and Europe, and "The Grass Is Green" in Germany.
It was announced on November 11, 2003 that Universal Music Group reached an agreement to acquire DreamWorks Records from DreamWorks SKG for "about $100 million". The purchase came at a time when the music business was "going through major changes" as it struggled to "counter falling sales and the impact of unofficial online music sales". Mo Ostin, the principal executive at DreamWorks Records, said: "Despite the challenges of the music business today, Universal is acquiring a wonderful asset and the sale will assure the strongest possible future for our artists". DreamWorks Records was folded into the Interscope Geffen A&M umbrella label in January 2004. Furtado's recording contract was then absorbed into Geffen Records.
Folklore received mixed or average reviews from critics. Allmusic's Stephen Thomas Erlewine stated that "[w]hile there are some interesting musical moments on Folklore -- enough to make it worth a listen -- the dogged seriousness and didactic worldview become a bit overbearing not long before the album is a quarter of the way finished, particularly since the fusion of worldbeat and adult alternative pop often seems heavy-handed."Entertainment Weekly gave a positive review stating that "exultant music goes on its merry, multicultural way". While Rolling Stone gave a negative review, calling Folklore "slick, multicultural hodgepodge" but "without a single as good as 'I'm Like a Bird.'" As she focused more on the songwriting rather "than on frenetically switching genres five times in one song",BBC felt that it had "twice the originality" of her debut.
The album debuted at number eighteen on the Canadian albums chart with first-week sales of 10,400, and at number thirty-eight on the U.S. Billboard 200 chart, selling 68,000 in its first week. According to Nielsen SoundScan, it had sold 425,000 copies in the U.S. by August 2008. It was not as successful as Furtado's debut album, Whoa, Nelly! (2000), partly because of troubles at DreamWorks Records and the less poppy sound. It lacked promotion because DreamWorks was sold to Universal Music Group at the time of Folkore's release, and it spent only eleven weeks on the U.S. Billboard 200 chart. In 2005, DreamWorks Records was shut down and many of its artists, including Furtado, were absorbed into Geffen Records. Furtado said, "Why do Germans love this album? I think I figured it out: It's so cerebral. It's great in its own way, but that's a different side."