The members of the Institute constitute a unique, worldwide association of statisticians, representing the various different branches of the statistical profession.

Elected members are elected by virtue of their distinguished contributions to the
development or application of statistical methods or to the administration of statistical services.

Ex-officio members are occupants of leading positions in official national statistical agencies and international organisations designated by the Council, or represent organisations affiliated with the Institute. 

Corporate membership is available to national or international statistical agencies, to certain cultural, educational and scientific institutions, and to commercial, industrial and business enterprises, which share or support the aims of the Institute. Corporate
members are entitled to designate two representatives who may attend the ISI Sessions and participate in the scientific programme of the Sessions.