This book is an abridgement and translation of Guillermo Lora's five-volume history. It deals with the strengthening and radicalisation of Bolivia's organised labour movement, which culminated in the drastic revolutionary changes of the 1950s. The first half offers a reinterpretation of Bolivian history in the century preceding the revolution, viewed from the perspective of the working class. The second half discusses in more detail the major political events and doctrinal issues of a period in which the author, as secretary of the Trotskyist Partido Obrero Revolucionario, himself frequently played an active part. Despite the radical upheaval that occurred in the fifties and the mobilisation of broad sectors of the population around such radical objectives as direct property seizures, union-nominated ministers and union, military and worker control, the labour movement was unable to maintain its conquests in the 1960s. The concluding chapters describe the period of renewed military repression and the continuing efforts of the labour movement to resist.