Essential for the success of the Council was the organization and decision-making within the "nationes". Not every representative of the nations belonged to the holy orders. University scholars or secular rulers were placed on an equal footing with the clerics.

With Italica, Gallicana, Germanica, Anglica, and Hispanica, five nations were represented in Constance. Each nation was supposed to act for all countries of one cardinal direction, even if they were at war with each other, or had different native tongues.

Here, on Black Friar Island, the French and the Italian nation held their meetings. In the former Franciscan monastery, today's "Stephansschule", the English and the German nation came together. The Spanish nation, having arrived later, moved into the Augustinian monastery round today's Trinity Church. The Council decisions were first discussed within the nations; representatives coordinated them with the other nations.

At the papal election of 1417, not only the cardinals but also nation representatives were entitled to vote. This unique measure ensured that the newly elected pope would be widely accepted.