The roots of the band were planted in 2003 when Ryan Lenssen and Adrian Jewett formed Thee Oneironauts. The pair recorded and self-released an EP entitled Night of the Lawnchairs on the GROK Studios imprint, which had also released Lenssen's concept band "Rushing To Redlights". The Oneironauts grew to trio status with the addition of Nick Greaves on guitar before ultimately becoming The Most Serene Republic. Their debut album Underwater Cinematographer was produced, mixed and engineered by Lenssen and mastered by Ryan A. Mills and recorded at ASF Studios. Its original release was in late 2004 on the independent label Sunday League Records before being picked up by Arts & Crafts. It was re-released on June 28, 2005 featuring new artwork. They were the first band signed by Arts & Crafts that was not related to Broken Social Scene in any way or form. After touring the album extensively with the likes of Metric, Stars and Broken Social Scene, the band recorded what ultimately became the Phages EP, that was first made available when the band supported The Strokes on their Canadian tour of 2006. In 2006 longtime drummer Adam Nimmo left the band, replaced by Tony Nesbitt-Larking. Tony appeared on Population and toured with the band throughout 2008. TMSR spent much of 2007 prepping their second albumPopulation, which was released by Arts & Crafts on October 2, 2007 to generally positive reviews. In 2007 Jewett and Lenssen appeared on MTV Canada to promote the release of Population. This would be the band's first television appearance. The two were interviewed during the airing of Making The Band wearing Star Trek outfits. During the interview they said they were on their way to a Star Trek Convention following the interview. In 2008 the full band appeared on MTV Live for an interview and three-song performance. In an interview from June 17, 2008, guitarist Nick Greaves stated that the band will be recording their third album with Broken Social Scene and Super Furry Animals producer David Newfeld, and hinted there might be a slight change of musical direction. 2008 saw the release of Live At XMU, a 4-song acoustic EP made up of songs from Population and Phages. It was recorded December 11, 2007 at the XMU studios in Washington, D.C.and released August 12, 2008 exclusively to iTunes. On April 20, 2009, the band announced their newest album, ...And The Ever Expanding Universe, would be released on July 14, and offered the album's second track, "Heavens to Purgatory", as a free download. In addition, they announced that an EP of 16-bit remixes entitled Digital Population would be released on April 28. On August 14 their song "Humble Peasants" was featured in the trailer for "A Generation After Genocide" a documentary about the healing power of soccer in Rwanda. Their video "Heavens to Purgatory" was directed by Ben Steiger-Levine and was nominated for Video of the Year at the 2010 Juno Awards. The band released "Pre Serene: Thee Oneironauts", a remastered compilation of material recorded by the band's direct ancestor, Thee Oneironauts in the latter half of 2003, on May 24, 2011. The Most Serene Republic have announced a return to action with their first new full-length album in six years, Mediac, which will arrive November 13 on MapleMusic Recordings. Mediac was recorded in Toronto, produced by TMSR's Ryan Lenssen, and mixed by David Newfeld.