When Dream and Day Unite is the debut studio album by American progressive metal band Dream Theater, released on March 6, 1989, through Mechanic/MCA Records.[1] The album is composed mostly of material that originally surfaced during the band's early years as Majesty, and it is the only Dream Theater album to be recorded with their full original lineup. James LaBrie replaced Charlie Dominici as the lead vocalist on all subsequent albums.

Charlie Dominici – lead vocals
John Petrucci – guitars
Kevin Moore – keyboards
Mike Portnoy – drums, percussion
John Myung – bass