By definition of the statutes, the directing body of OISTAT is the Congress, which is formed when the official representatives of the
member organisations, the OISTAT Centres, and individual members from other nations, are assembled in plenary session. Every four years, the delegates of the World Congress elect the President and the members of the Executive Committee. They also decide on changes of the statutes and other important issues of the organisation.
The next Congress will be in Cardiff, 2013