In 1976, world-class bluegrass players began converging on the Hudson Valley for an annual midsummer festival. As for the name and place, certain proprietary changes have been inevitable over the years; generations have passed, but the tradition remains much the same as it was 37 years ago. For the last 13 years, “Grey Fox Bluegrass Festival” has been the official brand name for what feels less like a music festival and more like a family reunion.

“I’ve played here since it was on that other mountain,” recalls bluegrass’s 74-year-old paterfamilias, Del McCoury. His eldest son, the mandolinist Ronnie McCoury, met his wife at the festival in 1985 when he was just 18.

“I’ve known Ronnie since he was 14,” says Grey Fox’s producer, Mary Tyler Doub, who renamed the festival for a painting in her bedroom. “I have a picture of him sitting, watching David Grisman play the mandolin…And, you know, Alison Krauss had her 17th and 18th birthdays here…and Chris [Thile], well, he’s been around since he was 8. I remember Sam Bush used to say to him, ‘Why don’t you just go out and play baseball?’”

Doub’s reminiscences are par for the course at Grey Fox.

“Oh, I met Sam [Grisman] when he was born,” said Ronnie McCoury with pride after the legendary mandolinist’s son played with The Deadly Gentlemen, a quintet whose high-voltage set earned them every bit of their name’s dark charm. Earlier that day, Danny Paisley – son of the late Bob Paisley, guitarist and singer for the Southern Mountain Boys – played with his band, Southern Grass, which includes his son Ryan on mandolin. At age 14, the youngest Paisley is already a sensational player, earning hoots and cheers from the crowd in sweltering heat.

Keller Williams & the Travelin’ McCourys (which includes Ronnie and his brother, the banjoist Robert McCoury) headlined Thursday night, playing material from their collaborative debut, Pick. Sans Keller, the McCourys returned to the stage the following day to play traditional bluegrass at breakneck speed, and then again later that evening in full regalia as The Del McCoury Band.

Friday afternoon introduced two acts whose stars rose quickly that weekend. The first was I Draw Slow, a five-piece band from Dublin with a gift for timeless storytelling set to a signature blend of Celtic and Appalachian music. The second was the Grammy-nominated cellist Rushad Eggleston, whose zany repertoire is, in equal turns, ridiculous and sublime. Both acts were reprised several times throughout the festival, culminating in the invitation of all six to join in on Saturday night’s all-star jam (featuring Tim O’Brien, Jerry Douglas, Chris Thile, Noam Pikelny, Bryan Sutton and others). Friday’s late-night sets were held down handily by the Infamous Stringdusters, The SteelDrivers, and The Duhks.

Pound for pound, Saturday delivered the motherload of mountain music, with 27 sets on three stages and 13 instructional workshops. High points included sets from Tim O’Brien, Jerry Douglas, and a blistering performance by Chris Thile & Michael Daves, who rip-roared through their new album, Sleep with One Eye Open, in time to string together an impromptu medley of fiddle tunes by request. Afterward, the Carolina Chocolate Drops played the evening headline slot (they’d shared the stage with zydeco phenom Cedric Watson earlier that day).

Additional acts highlighted over the weekend include the femmes fatale in Della Mae, Nora Jane Struthers and the Party Line, New York City’s own Six Deadly Venoms, and old-timey staples, The Dry Branch Fire Squad.

The festival ended Sunday afternoon as the 2013 class of Grey Fox’s annual four-day Bluegrass Academy (ages 8-17) took the main stage. Such so-called “family fun” is usually billed as a mild alternative to the main event. Not so at Grey Fox, bluegrass’s own royal family affair, where the commitment to preserving America’s traditional music is as hardcore as the drive to push it further.