The International SGML/XML Users' Group exists to promote the use of structured information markup languages such as SGML, XML, DSSSL, XSLT, HyTime, and XLink.

The Users' Group has a formal constitution, with provision for special interest groups (SIGs) and national/regional chapters. Several chapters and special interest groups have been set up, the former enabling people in a particular county or region to get together, the latter being for those who are interested in a specific aspect of the technology.

The membership elects a President to run the Group. Individuals and corporations may join the International Group directly and/or they may join a chapter. There are two classes of Chapter Membership: Affiliated, a separately constituted body; and Subsidiary, existing as part of the ISUG. Chapter members pay dues to the ISUG based on the number of individual and/or corporate members they have.

ISUG holds its annual general meeting at one of the conferences sponsored by IDEAlliance (formerly known as the Graphics Communications Association, or GCA).