The group announced in 2002 that it would end full-time touring at the end of the 2003-04 season so that members could pursue their individual interests.
Long Time Traveling, to be recorded next month, will feature 19th-century shape-note songs, spirituals, and gospel. Mandolinist Mike Marshall and fiddle player Darol Anger will make guest appearances.
The album will be released in fall 2006; the group will tour in summer 2006 and during the 2006-07 concert season.
Long Time Traveling is a follow-up to the group's 2003 CD American Angels, which also focused on American sacred music. That album was at number two on the Billboard chart last week, in its 67th week on the chart.
Anonymous 4 formed in the late 1980s and released its first recording in 1993. The group is credited with helping to spark a craze for medieval chant, and had a major hit, by classical standards, with 1997's 11,000 Virgins, a collection of music by the 12-century mystic Hildegard von Bingen.