VAIL, Colo. — On paper, the Vail Dance Festival looks more repetitious than it is. Lil Buck, Herman Cornejo, Tiler Peck and others return here year after year: Isn’t this just a club or clique?

When in Vail, though, what you see is how these returning artists extend themselves here — tackling new idioms, developing new partnerships, working on choreographic premieres — as nowhere else. You haven’t seen their full range if you’ve missed them here. And each year also brings new artists.

The festival itself, directed by Damian Woetzel since 2007, has been growing more sophisticated, ambitious and ethnically diverse. The International Evenings of Dance used to feature too many sets of 32 fouetté turns (the most renowned piece of ballet virtuosity) each evening; this year there were none. New choreography has always been a factor; but now multiple choreographers work here, show public workshops of pieces in progress, and even collaborate.

Who 10 years ago could have imagined two top-level choreographers making and dancing a duet together here? It happened on Friday, when Michelle Dorrance and Justin Peck joined forces for the world premiere of a tap duet, “They Try to Tell Us,” a perfect example of the sweet repartee that can turn tap, with its capacity for give-and-take rapid dialogue, into the medium of tenderly high-spirited feeling between two people.