From the site’s description:

Contra dance is a centuries-old New England folk dance tradition. It’s the rowdy red-headed stepchild of English country dance (the kind of dancing you see in Jane Austen movies). Contra dancing is done to live old-timey music in a variety of styles, from lilting Celtic-inspired tunes to rollicking bluegrass. All dances are taught by a caller, who “calls out” instructions throughout the dance.

San Francisco Bay Queer Contra Dance
http://www.lcfd.org/sf/index.html