The dancers link little fingers in a long line, swinging their arms, and moving to their left by taking longer steps in that direction than when stepping right. In the generic case the arm movements consist first of two circular motions going up and back (at about chest level) followed by one in the opposite direction (down then front); these are done quite close to the body. This is then followed by a circle in the same sense as the last (down then front) but with full arm extension and extending behind the body. The cycle then repeats.
Stepping is on the beat throughout, moving to the left on the close arm circles and in place (or sometimes to the right) on the second two. The stance is upright, with soft knees. A full set of steps takes 8 times, divided in two half-steps:
- 1st half-step, 4 times:
- 1st time: the left foot moves on the left
- 2nd time: the right foot joins the left foot
- 3d time: the left foot moves again
- 4th time: the feet don't move, the body still supported by the left foot
- 2nd half-step, 4 times:
- 5th time: the right foot joins the left foot
- 6th time: the left foot marks time (up & down in one time)
- 7th time: the right foot marks time (up & down in one time)
- 8th time: the feet don't move, the body stands on the right foot.
It is easy to do this dance within a short time of practice; this allows full beginners to quickly join the line during the festoù noz.
At a bal there will be several lines forming, with the leader leading his/her line in some pattern. The leader (person at the left-hand end of the line) will lead the line into a spiral or double it back on itself to form patterns on the dance floor, and allow the dancers to see each other.
An dros often have songs associated with them, and these are usually sung as a verse-chorus or call-response, with the leader singing the verses or calls. The musicians will sometimes play from the middle of the dance floor, and the dancers will then often form a spiral around them.