Boy is the debut studio album by the Irish rock band U2. It was produced by Steve Lillywhite and was released on 20 October 1980 by Island Records. Boy contains songs from the band's 40-song repertoire at the time, including two tracks that were re-recorded from their original versions on the group's debut release, the EP Three.

Boy was recorded from July to September 1980 at Dublin's Windmill Lane Studios, which became U2's chosen recording location during the 1980s. It was their first time working with Lillywhite, who employed non-standard production techniques, such as recording drummer Larry Mullen Jr. playing in a stairwell, and recording smashed bottles and cutlery skimmed against a spinning bicycle wheel. The band found Lillywhite to be very encouraging and creative, and he subsequently became a frequent producer of their recorded work. Thematically, the album's lyrics reflect on adolescence, innocence, and the passage into adulthood, themes represented on its cover artwork through the photo of a young boy's face.

Boy received generally positive reviews and included one of U2's first singles to receive airplay on US radio, "I Will Follow". The release was followed by the band's first tour of continental Europe and the US, the Boy Tour. The album peaked on the UK chart at number 52 in August 1981 and in the US at number 63. In 2003, Boy was ranked 417th on Rolling Stone's list of "The 500 Greatest Albums of All Time". In 2008, a remastered edition of the record was released.

Originally, Boy was slated to be produced by Martin Hannett, an in-demand producer at that time for his critically acclaimed work with Joy Division. Hannett had produced U2's first single with Island Records, "11 O'Clock Tick Tock", but the band did not enjoy working with him, and the prospect of him producing the album was abandoned by Island due to the band's objections. Hannett was also severely affected by the May 1980 suicide of Joy Division frontman Ian Curtis, the distress of which temporarily impaired his ability to work. Island A&R representative Nick Stewart said: "Martin by that stage was unwell; he seemed to be suffering from a little overdose of one thing or another."

Looking for a replacement producer, Island sent a copy of U2's first release, the EP Three (1979), to Steve Lillywhite to gauge his interest in working with them. Listening to the record, he "liked the voice" but thought "it didn't sound very good". Before deciding whether to work with the group, he wanted to see them perform live to figure out a potential creative approach he could take in studio. After visiting Ireland to attend a concert of theirs at a small school hall, Lillywhite was convinced to come on board, thinking, "Oh my God, there's something about this". He subsequently agreed to produce a single for them, "A Day Without Me". Although the song failed to chart, U2 found they could work amicably with Lillywhite and agreed to have him produce their debut studio album.

Boy was recorded at Windmill Lane Studios in Dublin from July to September 1980. Lillywhite was displeased with how the "A Day Without Me" single had sounded, particularly the drums, and decided to change how he recorded the band for the rest of the album. He found Windmill Lane Studios to be "very, very dead sounding" and thought it was more conducive to capturing quiet recordings of folk music than the energy of rock music; engineer Kevin Moloney concurred, calling the studio a "late '70s design, a very wooden dead kind of room". At that stage in his career, Lillywhite was interested in capturing "3D sound" that conveyed a perspective to the recording. While walking through the stone-walled reception area of the studio, he was impressed with how the space sounded and decided to record drummer Larry Mullen Jr.'s drum kit in the area's stairwell. Using microphones hung from the ceiling at the top of the stairwell, Lillywhite recorded what he described as "this wonderful clattery sound". They had to wait until the studio's receptionist went home in the evenings to record the drums, as the phone rang during the day. Even in the evenings, they were not allowed to disable the phone's ringer, resulting in it occasionally interrupting recording in the middle of a take. Mullen found the arrangement strange at first, as he was still acclimating to working with his bandmates together in a studio when Lillywhite set him up separate from the others.

Lillywhite employed a creative, experimental approach as the producer, recording smashed bottles and silverware skimmed against a spinning bicycle wheel for sound effects. The band found him to be very encouraging; lead vocalist Bono called him "such a breath of fresh air", while guitarist the Edge said he "had a great way of pulling the best out of everybody". The group's rhythm section struggled to keep time at that stage in their career, forcing Lillywhite and Moloney to spend extensive amounts of time at night splicing tape of the multi-track recordings to create drum loops that would be in time. Lillywhite recorded several bass parts played by Adam Clayton in order to teach Clayton the bassline that he ultimately wanted to be played. The approach necessitated Clayton recording many overdubs. With the band members still inexperienced at that point and manager Paul McGuinness giving them autonomy in their music-making process, Lillywhite speculated that he had more influence over the sound of Boy than any other producer of any other U2 album.

Some of the songs, including "An Cat Dubh" and "The Ocean", were written and recorded at the studio. Many of the songs were taken from the band's 40-song repertoire at the time, including "Stories for Boys", "Out of Control" and "Twilight". Without much studio time, the band quickly recorded each song, before spending a few hours on overdubs and moving onto the next song. Bono had not finalized his lyrics prior to the recording sessions; during the group's earlier live performances, he often changed lyrics from concert to concert, owing to his lack of interest in lyric writing. The procrastination forced him to finish missing couplets in the studio while his bandmates were busy recording guitars and percussion. Bono was displeased with the vocal performances that he gave in the studio when wearing headphones, and as a result, he changed his approach to sing into a handheld microphone in the control room while listening to playback of the music at high volume. After about six takes of each song, Lillywhite would edit together a composite vocal track of the best parts, after which Bono would listen back and replicate the results by singing another six takes.