Choral singers and Christmas go together like nutmeg and eggnog. They spice up the holiday by reminding you songfully about the Babe in the manger, the sparkles in the snow, and the holly in the halls. It’s the busiest time of year for ensemble singers, who take no small amount of pleasure in presenting the upbeat music from one of the world’s most upbeat seasons.

One such pleasure-loving group is the Bangor-based Impromptu! Its members include 10 talented singers whose vivacity for choral singing earns the exclamation point that always follows their group’s name. At a concert Saturday in Bar Harbor’s St. Saviour’s Episcopal Church, Impromptu! gave one of two holiday concerts it will offer this season. The second is this Wednesday at St. John’s Episcopal Church in Bangor, and if you’re planning on doing the concert thing this year, mark this celebratory event on your calendar.

In a 90-minute program that skips around from France to Spain to England, Wales, Africa, Puerto Rico and America, Impromptu! has an impressive level of sophistication when it comes to harmony and technique. The 20-plus repertoire includes church songs, pop songs, folk tunes and carols. The tones are always crisp and smartly articulated, which means, yes, you’ll understand every syllable even if it is in Latin or German or Spanish.

Clearly, this is a diligent and gifted group, given much of its guidance by vocal diva Bronwyn Kortge, a soprano who blows a little toot on her pitch pipe before each song, and serves informally as the concert’s director. Surely, however, a great deal of highbrow collaboration has occurred in this cheerfully skillful community group whose most formidable members include tenors Francis John Vogt and Luke Hedger, as well as bass singers Malcolm Burson and John Greenman. But the rest of the singers are no less valuable with their flowing voices and plucky friendliness.

Half the fun of the concert is watching the singers up close — how they gleefully form their sounds, how they beam back and forth at each other and friends or family in the audience, and how they simply rejoice in gratifying both themselves and other music lovers. Their spirits are high, and it makes for a lot of twinkling eyes and big smiles — not to mention good music.

Just about the time you want to belt out a few hallelujahs of your own, the members of the group invite you to join them in singing some well-known Christmas songs. It’s a fun ending to a festive evening, the likes of which you can only get in December.

Impromptu! will sing its heart out 7:30 p.m. Dec. 18 at St. John’s Episcopal Church on French Street in Bangor. For information, call 947-2835.