What about Mensa membership and attendance policies? Colloquiums are open to the public, but the AG is not, right?

Historically speaking, yes, that's true. In keeping with their educational mission, Colloquiums are always open to the public as well as members of Mensa. Annual Gathering attendance policy is set by each AG Committee, but most years — and in 2012 — guests of registered AG attendees (who are members) are welcome to attend. The only way to "wander in off the street" and attend an AG is to sit for the Mensa Admission Test, which is usually given at least once during the event. Such test-takers are often gifted a day pass so they can take advantage of the chance to see what the organization's largest event is all about. We hope that any nonmember Colloquium attendees will be intrigued enough by the day's program to come back and take the admission test at some point during the AG.