LENOX -- This year's Christmas concert by the Cantilena Chamber Choir comes at the intersection of two big anniversaries, with with a bit of the ensemble's long interest in Russian choral works -- and an overlay of holiday spirit.

The concert, on Sunday at Trinity Episcopal Church, will celebrate the centennial of Benjamin Britten's birth and acknowledge the 50th anniversary of Francis Poulenc's death with holiday-themed works from each composer.

"A lot of choirs are doing these two composers this year," said choir founder and director Andrea Goodman. But the 24-member choir will also perform a number of Russian works, based on Goodman's long interest in that tradition.

"We often like to do Russian pieces, because that's my specialty and the choir loves them," she said.

In October the choir celebrated Britten's work with a retrospective concert, and they will continue the celebration this Sunday by singing his "Chorale after an Old French Carol," a piece based on a 17th-century French melody with a text by the poet W.H. Auden. The piece was written in 1944 but largely forgotten until 1961, and performances are still relatively rare.

The choir will also perform Britten's "A Hymn to the Virgin" from 1930, one of his earliest sacred works.

Another piece pegged to a key anniversary is Francis Poulenc's "Four Christmas Motets" from 1952. Poulenc died 50 years ago.

Goodman described this as the most challenging piece on the program.

"The notes jump all over the place," she said, with lots of ups and downs and little room for error.

From the mid-20th century, the choir's program will shift back to the Russian baroque, with the "Virgin Unwedded" by Vasily Polikarpovich Titov, who lived an worked in the late 17th century and early 18th century. His work, much of which remains unpublished, includes many elements of late Renaissance music from Italy, but with distinct Russian adaptations.

"It's very spiritual, with a real depth to it," Goodman said. "It's more earthy, in a vodka-and-sack-of-potatoes kind of way."

The Russian tradition continued with works by Rachmaninov, one of the last pre-Revolutionary Russian composers to keep the sacred music tradition alive.

The program includes a selection from his Vespers, "Bogoroditze Devo," and the "Cherubic Hymn" from his "Liturgy of St. John Chrysostom."

Goodman has a particular affection for early Russian music, having a "lifelong fascination" that dates to a concert she heard in Vienna in 1988 by a chamber choir from Moscow.

That inclination led to a doctoral study researching the ways early sacred work remained alive in the aggressively atheistic climate of the Soviet Union. She wanted to know, "how did people know about it, and how did it survive?"

She found that the themes of sacred music survived in works by Russian composers, like Rachmaninov, and that scores were often hidden away in homes, the way families would have stashed religious icons.

"There were always composers who remember how the chant went," Goodman said. "People held on to the tradition."

With the collapse of the Soviet Union in early 1990s, the tradition came flooding back into the open.

She said it has been fascinating to work with the choir through the years on Russian work. Among the challenges is working with a difficult language like Russian, and the key points that must be kept in mind -- that a consonant ahead of an ‘e' has a ‘ye' sound, or that sung Russian puts greater emphasis on open vowels than the spoken language.

"I know it well myself," she said, and she enjoys imparting her knowledge about the music. "They imitate and have very good ears."

Rounding out the program, the choir will sing carols that are popular with their audience, like "Il Est Ne, le Divin Enfant," "Nouvel Nouvolet," and the "Berlioz Shepherd's Carol."

For some, they will invite the audience to sing along.

If you go ...

What: Cantilena Chamber Choir will present a Christmas program with music of Benjamin Britten and Francis Poulenc, Russian and French carols and sing-along

When: 3 p.m. Sunday

Where: Trinity Church, 88 Walker St., Lenox

Admission: $20 for adults; children get in free

Information: (518) 791-0185 www.cantilenachoir.org