Train of Thought is the seventh studio album by American progressive metal band Dream Theater, released on November 11, 2003 through Elektra Records.

Inspired by the audience response to Dream Theater's heavier songs while on tour, in the Chaos in Progress documentary, Portnoy says that they wanted Train of Thought to be a "balls to the wall" album with heavier, darker riffing, exposing them to a number of new metal fans. The album was written in three weeks. It was engineered by Doug Oberkircher and mixed by Kevin Shirley. Most of the album was played in concert for the Live at Budokan DVD. All songs from it have been played live to date.