The ISA is a federation of national and local slackline associations. Organizations which function as the sole representative of a country can join the ISA as full members, with delegates to the general assembly and voting rights. Regional and local organizations may join as partial members and will have the assistance of the ISA in developing a national organization. Observing members will be slackline companies, performance teams and other slackline professional organizations, as well as non-slackline organizations and companies.

All ISA members must be approved by the the association.