Membership in the Salt Institute is restricted to salt producing companies. This is narrowly defined as companies which both produce sodium chloride and sell sodium chloride. There are two classes of members, the distinguishing feature between them being their involvement in the North American salt marketplace where the Institute devotes a major share of its resources. Regular members are U.S.-based companies; non-U.S. companies can be invited to become regular members if they have significant North American market presence. Other member companies are Associate members.
Salt producers wishing to join the Institute should complete and submit an application form expressing their desire to join the Institute, a willingness to accept their membership and dues responsibilities, and including a description of their operations sufficient to establish that their company both produces and sells salt.