[3] Following Italy, San Marino adopted a party-list proportional representation electoral system on 15 October 1920.

Voters had to be citizens of San Marino, male, the head of the family and 24 years old.

By their part, landowners created a conservative party, the Sammarinese Democratic Union, campaigning for the return to pre-1906 institutions to restore order against strikes and political violence.

The Socialists refused to join the newly elected council, following a revolutionary political strategy.

On 11 January 1921, all Socialist seats were declared vacant due to absence and a by-election was held on 10 April, in which ten Christian democrats and eight conservatives were elected.