This book is about the History of the Socialist Party in the southeast of Santiago. An itinerary that begins in 1910 and ends in 1930, in which we reconstruct the party structure that its sympathizers developed, along localities, stations, colonies and obrajes. Leaders, newspapers and groups are the main acts of this tour, through the interior of a Mediterranean province of Argentina. Therefore, this work is a contribution to the studies on socialism in the Argentine provinces at the beginning of the 20th century.