"In the Summertime" is the debut single by British rock band Mungo Jerry, released in 1970.^[3] It reached number one in charts around the world, including seven weeks on the UK Singles Chart, two weeks on one of the Canadian charts, and number three on the Billboard Hot 100 singles chart in the US. It became one of the best-selling singles of all-time, eventually selling 30 million copies.^[4][5][6] Written and composed by the band's lead singer, Ray Dorset, while working in a lab for Timex, the lyrics of the song celebrate the carefree days of summer. The track was included on the second album by the band, Electronically Tested, issued in March 1971.

Dorset has said that the song only took 10 minutes to write, which he did using a second-hand Fender Stratocaster, while he was taking time off from his regular job, working in a lab for Timex.^[7]

The song was recorded in Pye Studio 1 with Barry Murray producing.^[8] Initially it was only two minutes long; to make it longer, Murray played the recording twice, slightly remixing the second half, and put the sound of a motorcycle in the middle.^[8] In an interview with Gary James, Dorset explained that they couldn't find a recording of a motorcycle, but that "Howard Barrow, the engineer had an old, well, it wasn't old then, a Triumph sports car, which he drove past the studio while Barry Marrit [sic] was holding the microphone. So, he got the stereo effects from left to right or right to left, whatever. And that was it."^[9]

The initial UK release was on Dawn Records, a new label launched by Pye. It was unusual in that it was a maxi single, playing at 331⁄3 rpm, whereas singles generally played at 45 rpm. It included an additional song also written and composed by Dorset, "Mighty Man," on the A-side, and a much longer track, the Woody Guthrie song "Dust Pneumonia Blues," on the B-side. As the record was sold in a picture sleeve, also not standard at the time, and sold at only a few pence more than the normal 45 rpm two-track single, it was considered value for money. A small quantity of 45 rpm discs on the Pye record label, with "Mighty Man" on the B-side, and without a picture sleeve, were pressed for use in jukeboxes. These are now rare collector's items.

In 2012, Dorset sued his former management company Associated Music International, run by his former friend and business manager Eliot Cohen, claiming over £2 million in royalties from the song that he believed had been withheld from him.^[10]

Credits adapted from the single liner notes for "In the Summertime".^[11]

• Ray Dorset – vocals, electric guitar, 6 string acoustic, cabasa, stomp
• Paul King – banjo, jug
• Colin Earl – piano
• Mike Cole – string bass

In 1970, Australian rock band the Mixtures covered and released the song. The song replaced Mungo Jerry's version at number one on the Australian chart, where it remained at number one for six weeks. It was the biggest-selling single by an Australian artist in Australia in 1970 and number three overall.

In 1995, Jamaican-American reggae musician Shaggy covered the song, and released it as the lead single from his third studio album, Boombastic (1995).^[54] Aside from the addition of rap lyrics, Shaggy's version also substitutes other lyrics for the song's original line "have a drink, have a drive." Shaggy also performed the song on an episode of Baywatch.^[55] A year after its release, the song was re-recorded and released specifically for the film Flipper under the title "In the Summertime" ('96 version).

The song's lyric "have a drink, have a drive, go out and see what you can find" led to its use in a UK advert for the campaign Drinking and Driving Wrecks Lives. It featured the first verse against people enjoying drinks in a pub during summer, then stopped to show a fatal car accident caused by drink driving.^[87] "In the Summertime" has been featured in many feature-length films including 29th Street, Twin Town, The Substitute, Drowning Mona, Mr. Deeds, Stolen Summer, Anita and Me, Wedding Crashers, Wild About Harry, Despicable Me 2, and Dog Days, and X.