Such curators may be permanent staff members, be guest curators from an affiliated organization or university, or be freelance curators working on a consultant basis.

In 1966, there were affiliated organization in 23 countries and corresponding members in 24 countries in which there were no affiliated groups.

By 1939 the movement claimed 4,697,915 members in 513 affiliated organizations nationwide.

The circles are also used with foundation approval to indicate other affiliated organizations.

In 2010, the organization included more than 450 active members coming from 55 countries and 18 affiliated organizations.