From Chris Cotter:

Sacred Harp is a uniquely American tradition that brings communities together to sing hymns and anthems in 4-part, a cappella harmony. We sing music from a living tradition stretching back over 200 years in a full-voiced and sometimes raucous style, while cultivating a democratic and participatory environment. All events welcome beginners and newcomers, with no musical experience or religious affiliation required — in fact, the tradition was born from colonial-era “singing schools” whose purpose was to teach beginners to sing and our methods continue to reflect this goal. Though Sacred Harp singing is not affiliated with any denomination, it is a deeply spiritual experience for all involved (and also lots of fun!).