Its dark lyrical content primarily reflects the demise of Blink-182, although it is stylistically upbeat and inspired by bands such as the Postal Service and the Cure.

Although anticipated by music press, When Your Heart Stops Beating undersold commercial expectations and received mixed reviews from critics.

By 2004, Blink-182, consisting of bassist Mark Hoppus, guitarist Tom DeLonge, and drummer Travis Barker, had achieved significant commercial success in the mainstream.

[2] The band had taken a brief break in late 2001 when DeLonge suffered a herniated disc in his back,[3] during which time he collected several darker musical ideas he felt unsuitable for Blink-182, compiling them into a record, Box Car Racer.

The album, recorded with the help of Hazen Street guitarist and longtime friend David Kennedy, was intended as a one-time experimental project but evolved into a full-fledged band upon Barker's involvement.

"[4] Blink-182 regrouped in 2003 to record and release their eponymous fifth studio album, which, not unlike Box Car Racer, reflected what critics believed to be a darker, more experimentalist tone.

[11] Following the 2004 Indian Ocean earthquake, DeLonge agreed to perform at Music for Relief's Concert for South Asia, a benefit show to aid victims.

[16] While away on a trip in April 2005, Hoppus participated in an interview with MTV News in which he revealed the band's existence, saying "Right now, Travis and I are using the time off to start this project called Plus-44 […] It's very exciting, like a breath of fresh air.

"[18] The band's name is a reference to the country code needed when placing a phone call to the United Kingdom, where Hoppus and Barker first discussed making music alone.

[17] Meanwhile, Hoppus invited friend Shane Gallagher to play guitar on a few tracks the band began working on, and he soon joined the group.

[19] Production on the record moved along swiftly once the duo purchased their own North Hollywood studio, which they dubbed Opra Music.

The space—which featured two recording rooms, a lounge and a small outdoor courtyard—was purchased in October 2005 from former Poison guitarist Richie Kotzen.

[19] Shortly afterward, friend Craig Fairbaugh came in to observe and listen and play to songs; he was later asked to become the fourth member of the group.

[31] According to Corey Apar of AllMusic, +44's original electronic influence is evident in the music, although it has "ultimately [taken] a backseat to guitar-driven rock".

[34] Ben Yates of Drowned in Sound felt that the album started strong with Blink-182-esque songs, however delved into "emo choruses and handed-down pop-punk riffs" for the bulk of the tracklist.

[37] The title track, "When Your Heart Stops Beating", features "snotty, mid-range British-sounding Telecasters" and was inspired by the story of Sid Vicious and Nancy Spungen — "you love your lady and outside of that, fuck everything else," according to Hoppus.

[37] "Lillian" features programmed drums and acoustic guitars, and was inspired by Hoppus' residence in San Diego, before the move to Los Angeles.

[37] "Cliffdiving" was inspired by Hoppus' teenage summers growing up, where he would embark upon his friend's house and dive into the pool from the rooftop.

It was placed as a musical break to separate the upbeat pop punk track "Cliffdiving" and the record's "darkest" song, "Weatherman".

[27] The song was initially dubbed "Puppy Killing Machine" — a name created by Heller that Hoppus deemed "so ridiculous" in relation to its upbeat, poppy nature.

As early as August 2005, Internet rumors began to circulate that the album would be released in January 2006 although the band's management denied the claims.

[38] Thanks to the duo's lack of press interviews, misinformation spread via the Internet in the months prior to the record's release, including fake songs purporting to be leaked tracks.

[21] "During that time, their former bandmate, Tom DeLonge, did the opposite, peppering blogs and magazines with quotes hyping his new band and putting the blame for the Blink situation squarely on their shoulders," reported James Montgomery of MTV News.

"[33] When Your Heart Stops Beating debuted at number 10 on the Billboard 200 in the United States on November 22, 2006, moving 66,000 copies in its opening week.

[30] The Washington Post described +44 as being in the same spirit as Blink-182 ("adorable, cuddly pop punk")[52] and The Gauntlet called the record the best post-Blink project.

[55] Channing Freeman of Sputnikmusic called the album "standard pop punk music", stating it was not a large departure from Blink-182.

Barker broke a bone in his arm during the band's music video shoot but managed to complete the performances, altering his kit set-up to accommodate.

[58] Doctors advised Barker to rest and not take part in the band's upcoming live dates, including early 2007 jaunts to Australia and Europe.

[57] The band spent April to June 2007 on the Honda Civic Tour of the US and Canada alongside Fall Out Boy, the Academy Is… and Paul Wall.

"Travis and I love our history with Blink-182, and it seems a shame to let those songs sit dormant forever because of what happened two years ago," said Hoppus on his blog.