Columbia does not have any Secret Societies. If it does, then they're pretty damned secret because no one knows about them. Columbia does have two very low-profile Senior Societies, the Senior Society of Sachems and the Senior Society of Nacoms. Most students don't even know the societies exist.
Each society taps 15 juniors each year, the Sachems by luring the candidates into an ambush where he or she gets hit in the face with pie, the Nacoms by convincing the candidate that he or she is in trouble.
Society membership tends to reflect powerful student leaders across the campus, and some seats develop 'lineages', passing on from one holder of a leadership position to the next.
The Sachems were responsible for a 2005 prank in which the Lerner Hall ramps were decorated with saffron colored banners to mimic Cristo's "The Gates" installation in Central Park.