A fan who attends an sf con buys a membership in that con and becomes a member. This terminology — in contradistinction to ticket — emphasizes that fans are expected to be active participants in the activities of a con and not merely passive consumers of entertainment.

In some cases, such as Worldcon and Windycon, convention membership also comes with membership and voting privileges in the sponsoring organization.

Membership may also refer to club membership.

While clubs may have membership cards, since some time in the 1960s, conventions have tended to have badges. For the first few decades of conventions, a membership card, numbered and signed by an officer of the convention, was issued. The custom started to disappear in the 60s and by the 70s membership cards were uncommon. (This may have been an effect of the increase in convention sizes. Individual membership cards are more practical for 150-member conventions than for 1500-member conventions.)