This essay analyzes the crisis of the Italian liberal regime in the early 1920s by adopting an institutional perspective. Before the Great War the Italian political system had reached a peculiar but relatively stable condition. This stability – which the essay describes in its first section – was based on a number of premises: a limited suffrage; the hegemony of the liberals; the absence of organized parties, or their limited and marginal role; the political relevance of the monarch. The liberal legal culture interpreted and at the same time legitimized this set of institutional arrangements. The second section of the essay describes how the Great War destroyed the elements mentioned before: universal manhood suffrage was introduced, liberals lost their hegemonic position, organized parties – notably the People’s Party and the Socialists – either were born, or grew in importance. The old rules that had governed the system until then did not hold any longer. However, the resilience of the liberal legal culture as well as the electoral and political relevance that the liberals were capable to preserve prevented the Italian political system from reaching a new stability based on organized parties – as is demonstrated by the lively political and constitutional debate of the early 1920s, notably on the new parliamentary regulations introduced in the Summer of 1920. The resulting institutional instability must be considered one of the factors that led to the fascist seizure of power.