Compiled by producer George Martin and the (then) three surviving members of the band, 1 includes the 27 Beatles songs that went to number one in the United Kingdom on the Record Retailer Top 50 chart or in the United States on the Billboard Hot 100 chart. It is worth noting, however, that the song "For You Blue" was listed on Billboard chart at number 1, along with the A-side "The Long and Winding Road", but Capitol Records treated "For You Blue" as strictly a B-side and did not promote it as an A-side. Meanwhile, "Day Tripper" was included on 1, since it charted at number 1 in the UK as a double A side with "We Can Work It Out", while in the US, only "We Can Work It Out" was number 1. The only singles released in both the UK and US that did not reach number 1 in either country, and were therefore ineligible for inclusion on the album, were "Please Please Me" and "Strawberry Fields Forever" (both reached number 2 in the UK charts, while in the US the former peaked at number 3, and the latter at number 8). The former was largely known as "The Beatles' first UK number one single"; however, it reached the top spot in the musical magazines New Musical Express and Melody Maker but not on the chart published by Record Retailer (now Music Week). On the other hand, "Strawberry Fields Forever" was part of a double A-side single along with "Penny Lane". This single had peaked at number 2 in the charts, behind Engelbert Humperdinck's single "Release Me".
This album is essentially a combination of both the US and UK versions of the earlier album 20 Greatest Hits, with the addition of "Something" (which was left off 20 Greatest Hitsbecause of time constraints). On 1, "Hey Jude" was released in its original full-length version (slightly over seven minutes); on the American version of 20 Greatest Hitsit had been released as a shortened version.