We've come to expect special moments at Neil Young's annual Bridge School benefit concerts. And this year's shows, which took place this past weekend, had more than their share, including an onstage reunion featuring on-again, off-again partners David Crosby, Stephen Stills, Graham Nash and Young.

The quartet hadn't shared a stage for nearly a decade, but as Rolling Stone reports, they anchored the festival's first night with a set that moved nimbly between established favorites like 'Teach Your Children' and 'Suite: Judy Blue Eyes' and recent or unreleased material like the new Stills song 'Don't Want Lies' (which you can watch above).

Crosby, Stills & Nash are frequently on the road, and full-scale reunions with Young are never out of the question, so it'll be interesting to see if this leads to anything more permanent.

The CSNY reunion led a strong and typically eclectic bill that included sets from fellow rock vets like Heart and Elvis Costello as well as appearances by younger acts like fun., My Morning Jacket and Arcade Fire; on the second night, the lineup welcomed Bridge School veteran Tom Waits. For more information about the Bridge School -- and a link to a complete stream of this year's shows -- visit their official site here.