Paul Kevin "Kevin" Jonas II (born November 5, 1987) - Lead guitar (usually a Gibson Les Paul) and background vocals. Kevin is the eldest of the band. Goes by Kevin rather than Paul. Kevin helped produce the bands' self-titled CD Jonas Brothers.

Joseph Adam "Joe" Jonas (born August 15, 1989) - Lead vocals, tambourine, guitar (in the song "A Little Bit Longer"). Joe is the "middle Jonas." He originally had no intention of becoming a singer; he wanted to be a comedian and work on the show All That.

Nicholas Jerry "Nick" Jonas (born September 16, 1992) - Lead vocals, guitar (usually a Gibson SG in the original red stain color), piano in the songs "When You Look Me in the Eyes" and "A Little Bit Longer," and drums in the song "Australia." Nick is the youngest brother in the band. On November 16, 2005 he was diagnosed with type 1 diabetes.

The brothers also have a younger brother: Franklin "Frankie" Nathaniel Jonas (born September 28, 2000), also known as the "Bonus Jonas" and "Frank the Tank." He will debut with his brothers on J.O.N.A.S!.