The event, known as Nudestock, is being hosted by the DeAnza Springs Resort near Jacumba.
Six bands are playing through Sunday at the resort for spectators who may or may not be wearing any clothing.
The resort's owner said the biggest misconception is that the festival and the resort itself is all about sex.
"We get a lot of that, and they're just uninformed. We are a family club. Just the total freedom, it's a great way to live," said the owner.
DeAnza Springs currently has about 700 members. That makes it the ninth largest nudist club in America.