The Boston Camerata, founded in 1954 under the auspices of the Boston Museum of Fine Arts, has long been one of the world’s premier early-music ensembles. Lutenist Joel Cohen, musical director since 1968, has recruited a large pool of vocalists and instrumentalists who have consistently earned high marks for the elegance, rigor, and immediacy of their interpretations. He has a reputation as an authority on performance techniques from the Middle Ages to the early Baroque, with emphasis on the French; he’s conducted the Camerata in a prizewinning recording of a medieval French Tristan et Iseult, for example, and in a requiem by 17th-century Provencal composer Jean Gilles. But unlike established groups overseas, the Camerata augments its huge European repertoire–which includes Elizabethan love songs, rare Jewish music from the Baroque period, and the sung poetry of Catalan troubadours–with pre-20th-century American music, long a neglected corner of cultural history. In fact, one of its biggest successes, and the one that brings it to Chicago this weekend, arose from this unusual focus: In 1995 the group collaborated with members of the Shaker community in Sabbathday Lake, Maine, to release a CD titled Simple Gifts, an anthology of Shaker spirituals from the late 18th and early 19th centuries that hit number one on Billboard’s classical chart. The purity and radiance of the music is spellbinding: Shaker tunes are forthright and plain, often sung a cappella and in unison like medieval Gregorian chants; most of the earliest are wordless, sometimes accompanied with gestures, clapping, or stamping, and those with lyrics generally testify to the sect’s faith in pacifism and simple communal living. Thousands of Shaker songs are preserved in archival manuscripts, and at this concert a vocal sextet from the Camerata and a quintet of Sabbathday Lake Shakers will perform several of Cohen’s recent transcriptions, as well as selections from the CD. Saturday, 8 PM, Mandel Hall, University of Chicago, 1131 E. 57th; 773-702-8068. Cohen will discuss Shaker music in the south lounge of the Reynolds Club (adjacent to Mandel) an hour before the concert, and an open Shaker worship meeting will be held Sunday at 11 AM in the university’s Rockefeller Memorial Chapel, 5850 S. Woodlawn.