Beginners fit right in on the floor of Island Center Hall.

The contradancers assembled at Island Center on a recent Saturday night fell into two camps: those who had, and those who have not, much.

Some of the 14 or so couples gathered for the event swish around each other with self-assurance and aplomb, forming and re-forming their little foursomes in geometric patterns that recall the snowflake configurations of a kaleidoscope.

Others fall off to one side of the lines of dancers or the other and turn at random, looking for all the world, like bumper cars – now colliding, now retreating, now turning in bewildered circles or standing stock-still, as if to move at all would invite disaster.

Here, laughter forms the common denominator – audible above the reels and jogs, it bespeaks the group’s pleasure in an activity that has roots in 15th century England.

“One of the fun things: I see little parts of the line (of dancers) fall apart and get back together again,” said Jennifer Youngman, the evening’s dance leader, or “caller.”

“The most important thing is smiling and having a good time,” she calls out to her charges.

Contradancing is similar to square dancing, with promenades, swings and allemandes. The difference is the number of dancers; square dancing is restricted to four couples, while contradance welcomes whatever the hall will hold, with the dancers forming two parallel lines the length of the room.

Contradance repertoire comprises traditional jigs and reels from the Scots-Irish tradition on both sides of the Atlantic.

The job of the band is to keep the rhythm strong, says Port Townsend banjo player Jeanie Murphy who, with Scott Marckx and Ken Embrey make up the Puyallup Valley String Band.

Murphy encountered contradancing as a child in rural Lincoln, Mass.

“A famous caller, Ted Sanella, worked at Lincoln drug store,” she said. “Every Thanksgiving we’d have a contradance at the elementary school.”

Murphy was introduced to one of two American strains of the dance, both imported with the early colonists. The popularity of the form peaked around 1800, but was supplanted in urban areas by couple dances like the waltz and the quadrille.

The dances was preserved in rural New England and in Appalachia. Northern and southern contradance diverged, with the New England strain hewing closer to the British roots, while the Appalachian form absorbed the African rhythms of the slaves.

“The northern tunes tend to be ‘notier’ and less rhythmic,” Murphy said. “The northern tunes feature the piano; the southern, the banjo.”

Puyallup Strings plays around Puget Sound, but prizes the Island Center venue for intimacy and friendliness, Murphy says.

Having acquired some expertise and a good deal of aerobic exercise, the dancers wait, somewhat breathlessly, between dances to be taught the next move.

“It is customary at contradances to feel free to ask anyone to dance,” Youngman instructs the dancers.

“If you haven’t already said ‘hi’ to your neighbor, do so now.”