Following Nimrod, Green Day decided to continue on their experimental path. The band chose to work with producer Scott Litt instead of their long-time collaborator Rob Cavallo; however, the arrangement fell through and they produced the album themselves. That gave them the freedom to experiment with different sounds and styles and to focus on the songwriting, which they wanted to be very organic. It was not all fun and games, though; Mike commented on the pressure that producing puts on you by saying, "It's like wearing ten different hats at the same time."

   Warning was released on October 3, 2000. The critical reception to the classic-rock inspired semi-folk pop record was mostly positive, with reviewers noting the maturity of the band’s sound. Acoustic guitar was utilized like it had never been before, and apathy was no longer the name of their game: Billie Joe’s lyrics were now both more introspective and aware of the current social climate. Rolling Stone wondered about the band’s new direction: "Warning... invites the question: Who wants to listen to songs of faith, hope and social commentary from what used to be snot-core's biggest-selling band?"

   Commercially the album did not fare as well as any of the band’s other major label releases, though it did reach number four on the Billboard 200 and did eventually go gold. The record’s first single “Minority” reached number one on the US Modern Rock chart and its video received significant television airplay. The other singles, "Warning" and "Waiting" were less successful.

   After stints on the Warped Tour, Green Day embarked on an international tour and played all throughout 2000 and 2001. The band also played at CBGB’s and took home eight California Music awards including Outstanding Album (Warning), Outstanding Punk Rock/Ska Album (Warning), Outstanding Group, Outstanding Male Vocalist, Outstanding Bassist, Outstanding Drummer, Outstanding Songwriter and Outstanding Artist.

   About this time, a second wave of pop punk bands -- such as Blink-182, Good Charlotte and Sum 41 -- broke into the mainstream and several critics wondered what this meant for their predecessors, Green Day. Most people assumed that Green Day’s commercial appeal had long since waned and that their peak was far past. This almost seemed to be confirmed by the band itself with the release of the dreaded greatest hits album, International Superhits! (November 13, 2001) and b-sides compilation, Shenanigans (July 2, 2002). It did not help that there were rumors that the band was on the rocks. (In later interviews Mike and Tre admitted to feeling like Billie was purposefully overshadowing them; they said that they talked through the issues.)

   In 2002, Green Day co-headlined the Pop Disaster Tour with Blink-182. This reignited some interest in the band and got them featured on MTV and in the documentary Riding In Vans With Boys. Because Blink was more popular at the time, Green Day opened for them; this lead to some tension between the bands, especially when Green Day’s performances were better reviewed. One reviewer who wasn’t even a fan of Green Day admitted: "If Green Day were an orgasm, Blink 182 were a bit of an anticlimax." There were also tales of people leaving the show after Green Day finished without even bothering to watch Blink’s set. (Blink singer/guitarist Tom Delonge later commented on the rivalry between the bands by saying that is was more a "Tre thing" than a "Green Day thing.")

   The Pop Disaster tour helped the boys get back into the swing of touring and got the pumped up for writing new material…