While some wander around in alien costumes and others defend their UFO research, the festival is generally aimed at providing food, entertainment and a little education.
It was 1947 when the so-called Roswell Incident drew attention to this desert town. A crash north of Roswell spawned decades of debate, which still continues.
Was it merely a weather balloon, as the government claimed, or a UFO?
Event coordinator Julie Shuster said the main goal is for people to have a good time.
"If they learn something about the UFO phenomena or the Roswell Incident while they're here, then even better," she said.
Visitors can check out the UFO Museum and Research Center or special festival events, like a parade, concerts, pony rides for kids -- and a workshop on alien mind control techniques.
