Chelsea was NOT in a GLO. I was out one night with a friend who attended Satnford and his college friends were with us. Chelsea was sort of in their crowd - would go out with them occasionally. He and Chelsea have also exchanged a few emails since graduation. We got talking about sororities, I mentioned mine, then asked if she was in one and he said no. Also, like S&S said, we would have probably heard a lot about it by now.
Side note - He also told me a story about how they were out at the beach one day and someone had a cigar. A cigar discussion ensued and Chelsea said, "My dad always is smoking cigars. It drives my mom crazy!" Made for great irony when telling the story in 2002!!!