Today is the anniversary of the coup that overthrew president Salvador Allende in Chile and installed the brutal Pinochet dictatorship. We publish here a document written in 1979 by Alan Woods analysing the history of the Chilean labour movement and specially the period of the Popular Unity coalition government of Allende. Who was behind Pinochet's coup? What interests was he defending? What were the policies of the Allende government and why despite all warnings was he unable to prevent the coup?