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. As Contemporary Christian Music (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..."