By Caldwell Titcomb

The Emerson String Quartet offers an unusual program this month.

Dec. 1: The Tufts Early Music Ensemble, including singers and instrumentalists, will present a free concert of secular music by the great 15th-century composer Guillaume Dufay and his contemporaries, whom we rarely get to hear in live performance. Distler Performance Hall, Granoff Music Center, Tufts University, 8 p.m.

Dec. 2: The Chiara Quartet, in residence at Harvard, begins a six-concert cycle of the complete Beethoven quartets, kicking off with Op. 18, No. 4 in C-minor, Op. 59, No. 1 in F-major, and the last quartet, Op. 135 in F-major. The concert is free, but the required tickets are available at the Harvard Box Office in Holyoke Center, Harvard Square. Paine Hall, 8 p.m.

Dec. 2-5: The Boston Symphony Orchestra’s roster of conductors has been erratic so far this season. But if the announced schedule pans out, Christoph von Dohnányi will lead a wonderful program of Bartók’s “Divertimento for String Orchestra,” Martinů’s “Violin Concerto No. 2″ (with Frank Peter Zimmermann as soloist), Dvořák’s magnificent Symphony No. 8. Symphony Hall at varying times.

Dec. 3: The International Contemporary Ensemble, founded in 2001 and devoted to new music, offers a free concert of works by the late Iannis Xenakis, Philippe Hurel, Steven Reich, Sir Harrison Birtwistle, Elliott Carter, Jonathan Harvey, and MIT faculty member Keeril Makan. Killian Hall, MIT, at 8 p.m.

Dec. 4: The Emerson String Quartet, under the auspices of the Celebrity Series, offers an unusual program including Ives’ String Quartet No. 1, Janacek’s Quartet No. 1, and Shostakovich’s Quartet No. 9 in E-flat, Op. 117. Also scheduled is Barber’s famous Adagio, usually played by a string orchestra to memorialize a death, but originally written as a quartet movement. Jordan Hall at 8 p.m.

Dec. 7: The New England Conservatory continues its free “First Monday” concerts with two clavichord pieces by J.S. Bach and his son Wilhelm Friedeman; Couperin’s “Ritratto dell’amore” for flute, cello & harpsichord; Brahms’ Piano Trio in C-major, Op. 87; and the late Karlheinz Stockhausen’s “Kontakte” for piano, percussion & electronic tracks. Jordan Hall, 8 p.m.

Dec. 8: The Boston University Symphony Orchestra under David Hoose follows the Overture to Verdi’s “Vespri Siciliani” with the Boston premiere of John Harbison’s “Concerto for Bass Viol and Orchestra” (with the BSO’s principal bassist Edwin Barker as soloist), and concludes with Schumann’s Second Symphony. Tsai Performance Center, 685 Commonwealth Avenue, at 7:30 p.m..

David Hoose conducts the Boston University Symphony Orchestra

Dec. 11: The Boston Conservatory Wind Ensemble, led by Eric Hewitt, performs Stravinsky’s “Symphonies of Wind Instruments” and “Octet,” along with Kurt Weill’s Violin Concerto (Markus Placci as soloist) and Hindemith’s “Symphony in B-Flat for Concert Band.” The free concert takes place at the Midway Studios in South Boston at 8 p.m.

Dec. 12 & 20: The Boston Camerata, conducted by Joel Cohen, presents “A Mediterranean Christmas,” consisting of unfamiliar works from France, Spain and Italy, including the regional premiere of music by Francesco Mancini (1672-1737). The Dec. 12 performance takes place at the First Church in Cambridge at 8 p.m., the Dec. 20 performance at the First Lutheran Church in Boston (Berkeley & Marlborough Streets) at 3 p.m.

A free concert commemorates the 50th anniversary of the death of the great Czech composer Bohuslav Martinù

Dec. 13 & 14: The Harvard University Choir always sings admirably and offers its 100th Annual Christmas Carol Service twice this year. The Sunday performance is in Memorial Church, Harvard Yard, at 5 p.m., with a repeat on Monday at the Church of Our Saviour, 25 Monmouth Street, Brookline at 8 p.m.

Dec. 21: The Longy School of Music commemorates the 50th year of the death of the great Czech composer Bohuslav Martinù (1890-1959) with a free concert of music by him, his pupil Vitezslava Kapralova (1913-40) and her father Vaclav Kapral (1889-1947). Vocal and chamber works will draw on two sopranos, a pianist and cellist. Pickman Concert Hall, Longy School , 27 Garden Street, Cambridge, 7:30 p.m.