When We All Fall Asleep, Where Do We Go? is the debut studio album by American singer-songwriter Billie Eilish. It was released on March 29, 2019, by Darkroom and Interscope Records in the US and Polydor Records in the UK. Eilish, aged 17 at the time of release, largely wrote the album with her brother Finneas O'Connell, who produced it at his small bedroom studio in Highland Park, Los Angeles.

Musically, When We All Fall Asleep, Where Do We Go? is a pop, electropop, avant-pop, and art pop record, though it also features influences from hip hop and industrial music. Its songs explore themes such as modern youth, drug addiction, heartbreak, suicide, and mental health, with lyrical sensibilities of humor and horror. The album's title comes from a line in the song "Bury a Friend". Eilish said the album was inspired in part by lucid dreaming and night terrors, which are reflected on the cover photo.

The album was marketed with the release of seven singles, four of which received multi-platinum certifications in the US—"You Should See Me in a Crown", "When the Party's Over", "Bury a Friend", and the worldwide hit "Bad Guy". Eilish also embarked on several tours in support of the album, including the When We All Fall Asleep Tour and the Where Do We Go? World Tour. An immediate commercial success, the album topped record charts in many countries during its first week of release. By June 2019, it had sold more than 1.3 million copies in the US and became the year's best-selling album in Canada, while in the UK, it had made Eilish the youngest female solo act to chart at number one.

Upon release, When We All Fall Asleep, Where Do We Go? received universal acclaim and was one of the year's most acclaimed albums. Many reviewers praised its subject matter, songwriting, cohesiveness, and Eilish's vocal styling. At the 2020 Grammy Awards, it won Album of the Year, Best Pop Vocal Album, and Best Engineered Album, Non-Classical, while "Bad Guy" won Record of the Year and Song of the Year; Finneas also won the award for Producer of the Year, Non-Classical. In 2020, the album was ranked at 397 on "Rolling Stone's 500 Greatest Albums of All Time" list.