GLAD is one of the pioneers of Christian pop/rock and a cappella music, having formed as a progressive rock group in 1972 and discovered a large audience for their a cappella music in 1988. Today, with over 1.5 million albums sold, they continue to perform concerts and release occasional recordings. The Sun-Sentinel noted that when most contemporary Christian music reflected the "showbiz" style of Southern California or Nashville's country or gospel music, GLAD emphasized jazz, rhythm & blues, and fusion. As CCM Magazine described it, "GLAD's elegant vocals helped set them apart from other pioneers of Contemporary Christian music. That vocal sound has since evolved into a complex, self-sustaining life form of its own..."