This book, written collaboratively by three authors, is the product of research conducted at different times by its writers. It aims to study these types of government present in South America from the late 1950s to the 1970s, using three groups: 1) Restricted democracies, which include the cases of Colombia and Venezuela in parallel, and Uruguay with its differentiated characterization; 2) Democracy in Chile, from the triumphant perspective of the Popular Unity; and 3) The dictatorships of the Southern Cone, with emphasis on Argentina and Chile. Likewise, the reader will find some general conclusions that will allow, beyond a synthesis, to elucidate transition models for rethinking not only the 1960s but also the second half of the 20th century, regarding democracy as a process.