Anyone may belong to the Library. There are no requirements of residency and there is no need to be nominated by a member. Membership is diverse in age, income, and cultural background. The historic name of the Library is the Young Men's Mercantile Library Association, but women have been members for more than a century. Members are united by an interest in the printed word.
The basic annual subscription is $45. Household membership entitles all members of a household to use of the Library. Members of the public are invited and encouraged to visit the Library, but use of the collection and reading room is restricted to current subscribers.