Kerplunk (also known as 'Kerplunk!') is the second full-length album by punk rock band Green Day. It was released on January 17, 1992 on Lookout! Records. Kerplunk was their last release on an independent label and was also the first album to feature their current band lineup with Tré Cool on drums. The album went on to become one of the highest-selling indie albums ever. Major labels took notice of Kerplunk's phenomenal popularity and many approached the band. Green Day realized that they had outgrown their record distribution capacity with Lookout! and eventually signed with Reprise Records. With Reprise, Green Day would record and release their third album Dookie (1994), which would become a landmark album of the 1990s with over 10 million units sold in the U.S. alone.

The album officially includes only 12 tracks, but the versions released on CD and cassette also include the 4 tracks from the Sweet Children EP. One of those 4 tracks is a cover of The Who's "My Generation". Another notable track on the album is "Welcome to Paradise", which the band would re-record for their next album Dookie.

As of November 2006, Kerplunk has sold 699,001 units in the US , and over 4 million worldwide.

In August 2005, Green Day pulled this album, as well as all of their other material released through the label, from Lookout! due to unpaid royalties. It was reissued by Reprise Records, who Green Day has been with since leaving Lookout!, on January 9, 2007. Note that in Europe, the album was released by Epitaph Europe, and has remained in print. In December 2007, Blender magazine ranked Kerplunk #47 on their list, "The 100 Greatest Indie-Rock Albums Ever."