Concom is fanspeak for "convention committee," a group of volunteers who organize a con also frequently called just the committee..

This is the committee of conrunning fans who handle the details of any arrangements with the hotels, arranging the program, selecting 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 often has several hundred.

Since the term concom did not appear in Fancy 2, Leah Zeldes Smith speculated in STET 9 that it was "Probably post-1950s. Possibly dating from the 1970s, when the big explosion of conventions occurred." However, Jim Caughran says, "I seem to remember it from the 1950s, but I can't confirm that. Anyone?"

Concom is often used informally to refer to everyone who works to make a convention happen, but it typically consists of the area heads (sometimes called "department heads") and others with decision-making authority. Some cons count staff members as part of their committee, but others do not, and gophers are not normally considered part of the formal concom. Concoms are normally headed by a chairman (though groups of executives are sometimes used and occasionally more fanciful terms are employed).

British and American usage differs, with the British tending to use it to refer more to the leadership or managers of a con, while Americans tend to use it for everyone working on the convention. Though even that is far from universal.

Level Comments
Chairman Nearly all conventions have one, though occasionally with some other title.
Division Heads Needed only at Worldcon, though some regional conventions have this level to make up for a weak chairman or to provide high-sounding titles to accommodate the group's internal politics.
Area Heads Needed at all but the smallest conventions.
Staff At the smallest conventions may merge with Gophers.
Gophers Most cons need lots of them.