"I Know What You Did Last Summer" was written backstage spontaneously on one of
Taylor Swift's
The 1989 World Tour stops, in which Mendes was an opening act and Cabello was the surprise guest as part of the group
Fifth Harmony. "We were just backstage. There were like 100 people in my dressing room at the time, and it was madness back there, but I had this guitar and I was just jamming out, and we basically wrote a pre-chorus and a chorus in like 30 minutes," Mendes said in a video released about the making of this song. "And we planned to go into the studio, and it was like an 11-hour studio session where we finished writing the song." After a live performance on Live with Kelly and Michael, Cabello said, "We were just kind of jamming out. We weren’t really just writing a song. We kind of started spitting out melodies and put lyrics to it; I don't think we knew we had a song."[1][2]
The artists co-wrote "I Know What You Did Last Summer" with its producers
Ido Zmishlany and
Noel Zancanella, with
Bill Withers receiving songwriting credits for the sampling of his 1971 single "
Ain't No Sunshine" and
Ryan Tedder also receiving songwriting credits. Cabello described "I Know What You Did Last Summer" as a "conversation between two people in a relationship where it's dying, but nobody wants to admit that it's dying."[1] The song is sung in
A minor, and set in common time with a tempo of 114
bpm.[3]
Commercial performance
"I Know What You Did Last Summer" debuted at number ninety-seven on
Billboard Hot 100 for the chart dated December 5, 2015 and jumped to number fifty-five on the following week. On the week ending January 9, 2016, the song jumped from number forty-six to number thirty-three. The song has since peaked at number twenty for the chart dated January 30, 2016, becoming Mendes' second top 20 single, after "
Stitches", which peaked at number four on October 31, 2015.
Music video
A
music video for the song was released on November 20, 2015, and was directed by Ryan Pallotta. In the video, Mendes and Cabello, ages 17 and 18 respectively at the time of the making of the song and filming of the video, are seen walking through a dark and desolated landscape. They keep trying to walk towards each other but aren't moving. They are seen weathering a sandstorm, followed by a snowstorm and a rainstorm which culminates in a standoff of sorts.[2] The music video has over 412 million views and 4.1 million likes as of January, 2024.
Mendes and Cabello also performed the track while on the 2015 iHeartRadio
Jingle Ball tour in December, on the following dates: 1, 4, 11, 16, 18 and 19.
Mendes has added the single to his setlist on his ongoing tour,
Shawn Mendes: The Tour, as a medley with "
Señorita"—which Cabello also features in—and "Mutual". The single was also added to his setlist on his first solo concert tour,
Shawn Mendes World Tour.
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ČNS IFPI" (in Czech). Hitparáda – Radio Top 100 Oficiální. IFPI Czech Republic. Note: Change the chart to CZ – RADIO – TOP 100 and insert 201621 into search.
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ČNS IFPI" (in Czech). Hitparáda – Digital Top 100 Oficiální. IFPI Czech Republic. Note: Change the chart to CZ – SINGLES DIGITAL – TOP 100 and insert 20161 into search.
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ČNS IFPI" (in Slovak). Hitparáda – Radio Top 100 Oficiálna. IFPI Czech Republic. Note: insert 20167 into search.
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ČNS IFPI" (in Slovak). Hitparáda – Singles Digital Top 100 Oficiálna. IFPI Czech Republic. Note: Select SINGLES DIGITAL - TOP 100 and insert 20161 into search.