Villaneuva's first entrance into the New York hardcore scene came when playing in bands including Demonspeed and Murphy's Law.
In the fall of 1999, Thursday's lead vocalist, Geoff Rickly, approached Villanueva to produce the band's Eyeball debut Waiting.
Following the success of Thursday's Full Collapse, Victory Records approached Villanueva to work with and develop Long Island emo band, Taking Back Sunday.
The band's debut album, Tell All Your Friends, sold over 900,000 copies and became Victory's fastest and biggest selling record to date.
Taking Back Sunday's Notes from the Past also contains a song called "The Ballad of Sal Villanueva".