The number of active members of each country taking part in the Commission is established by Statute. That number changed (see Statutes), in relationship to the density of cities present in the countries and to the development of studies in urban history. The number of countries represented in the Commission also changed in that period, above all as a consequence of the geopolitical transformation after the fall of the Berlin Wall, Soviet Union and Yugoslavia.

In the early decades of the Commission life, when the dominant language of European culture was French, meetings were conducted exclusively in French. Afterwards, approximately at the beginning of the 80’s, English and German became the principal languages, next to French.

An important reform of the Statute has added honorary members, whose number is unlimited. Honorary members have the same rights as active members, but not the same obligations.

In the 90’s intercontinental members also were added, without voting rights, in the General Assembly. They broaden the scientific and methodological horizons of the Commission and build a cultural bridge between Europe and the rest of the planet.

The Atlas Working Group (AWG) was born at the beginning of the new Millennium. The AWG is constituted both by members of the Commission and affiliated members, i. e. external scholars, who contribute with their researches to the development of the Commission’s work on the Historical Atlases. The number of AWG members is unlimited.