The tune was their first #1 hit on Billboard's pop chart and marked the beginning of the British Invasion with its 15-week stay in the Top 50. It was also an innovative recording for Lennon, McCartney, George Harrison and Ringo Starr � their first cut on four-track gear.

"I Want to Hold Your Hand" was not only a success, it was a calculated one. The band's manger Brian Epstein � troubled by the group's lack of presence in America � asked Lennon and McCartney to write a song that would appeal to the U.S. market. Anticipation on both sides of the Atlantic was high when the disc's imminent arrival was announced. One million copies were ordered by retailers in advance.

The harmonized vocal chord that opens the song � as sweet a hook as was ever written � came first as Lennon and McCartney sat laboring at the piano in the London home of McCartney's girlfriend Jane Asher. The rest was pure Tin Pan Alley, or maybe Leiber and Stoller: a slick song about innocent love written with two bridges and a single verse to connect them. And like many early Beatles tunes it had no lead singer per se, instead putting McCartney and Lennon's twined harmony voices to the fore, with Lennon having a slight edge in the mix.

Although Lennon and McCartney were still several years away from their mutual romance with Epiphone Casinos, multi-tracking helped The Beatles and their producer George Martin create a dense guitar sound that was unlike anything previously recorded in the UK.

"I Want to Hold Your Hand" also differed from most early rock hits � like "Hound Dog" or "Rock Around the Clock" � in that the tune wasn't written by the kind of non-performing professional songwriters who labored in the Brill Building and wrote most of the popular songs of the day. Together with Bob Dylan, The Beatles changed the image of rockers as mere performers to that of complete artists who could not only play but also write and record their own material.

The sessions for "I Want to Hold Your Hand" began on October 17, 1963 at London's EMI Studio 2, which was equipped with a new four-track tape machine. The tune took 17 passes to complete. In an odd twist of marketing, a second version was cut in January 1964 with a vocal performance in German. The group had built up a sizeable following in Hamburg and elsewhere in Germany during their club apprenticeship, and Odeon, the German arm of their label EMI, insisted the single be cut in that tongue.

"I Want to Hold Your Hand" was one of two singles The Beatles were compelled to re-record in German. The other is "She Loves You." Both were done against their wishes, and history has proven The Beatles' resistance correct, since the English language versions of the tunes have remained the most durable everywhere in the world.

When "I Want to Hold Your Hand" was released on November 29, 1963 in the U.K., it rocketed straight up the British charts. On December 14 it bumped another Beatles song, "She Loves You," out of the #1 spot.

Despite that chart performance, EMI Record and Epstein had to battle the group's American label Capitol Records to release "I Want to Hold Your Hand" as The Beatles' first U.S. single. When Capitol caved, the song was paired with "I Saw Her Standing There" as the B-side and hit America on December 26. Epstein further insisted the label spend $40,000 to promote the single to DJs and retailers with advertising in trade magazines and on the airwaves.

Initially Capitol planned a January release, but a canny Washington, D.C., disc jockey got a copy a few weeks earlier via British Airways and began spinning the song, which generated so much listener excitement that the label was forced to jump into action with the late December date. Capitol's first reaction was unprecedented: the label threatened to seek a court injunction to prevent airplay, which rapidly spread to Chicago and St. Louis. Ultimately, they decided to co-opt the anticipation that the media reporting about the airplay flap generated into the single's promotional campaign.

By December 29, after just three days of sales, "I Want to Hold Your Hand" had sold more than 750,000 copies, averaging 10,000 a day in New York City alone. Overall the song sold more than 5 million copies in the U.S. on its initial release.