Convention committee, a group of volunteers who organize a con.
Short for CONvention COMmittee. These are the fans who handle the details of putting on any give convention–making arrangements with the hotels, arranging the program, selected guests, encouraging participation, providing technical or other services. The smaller the convention, the fewer fans are needed to make up a ConCom –- there have been a few in our history in which only one fan did all the work. Many early Worldcons had as few as two or three people on the Convention Committee. The modern Worldcon can (and most often does) have a few hundred.
Contributors: Jim Caughran, Dr. Gafia
Leah says "Probably post-1950s. Possibly dating from the 1970s, when the big explosion of conventions occurred." Jim Caughran: I seem to remember it from the 1950s, but I can't confirm that. Anyone?