This essay focuses 011 the essential chro110/ogy cmd the most sign(/icant historiographical questions conceming Socialism in the earlv postwaryears in Trieste until the march on Rome. My analysis has been conducted on two socialist newspapers of the time, «Il Lavoratore» and «Il Lavoratore socialista>>. The First World War and its consequences has a deep infuence also on the Socialisl movement in the transition from the Austro-Hungarian Empire to the after war Italian administration in the Eastern border of Italy. This study of its elaborate history intends to contribute to clarify the political and social events of the postwar years in Trieste and its territory.