This case study of alternative, radical journalism in Latin America during the 1970s, seeks to clarify and define the characteristics and limits of this model in concrete, specific historical circumstances. It traces the history of Alternativa, a leftist magazine published between February 1974 and 1980 in Bogotá, Colombia when three groups of people from different backgrounds devised a journalistic alternative model based on four objectives (counter-informing; investigation, analysis and interpretation; divulging the people's struggles; and propitiating the unity of the left), to effect a lasting change in Colombia's society. The founders' common Marxist background determined the magazine's content and its approach. Initially, they declared themselves independent and neutral toward the left's groups and decided to reach a wide audience through mass circulation. The narrative shows how inner tensions resulting from principled differences among the magazine's creators and from political circumstances led to two crises that tested its founding principles and determined its journalistic evolution. It also shows the struggle of the magazine to survive in a hostile climate, against a notoriously reckless and corrupt regime, testing the limits of the freedom of the press. In the first phase, the narrative reviews the history of the country as seen through the eyes of the publication, which contested the official version in the mainstream news media. In the second phase, the investigation highlights paramount issues such as human rights violations, corruption and the role of the press, through the magazine's critical coverage of Colombia's armed forces and police. In the third phase, the dissertation explores the magazine's complex relationship with the left, which eventually led to its demise. As author of this dissertation, I was witness to the events covered by Alternativa, and was part of the staff of writers in the magazine's third and last stage, with an inside view of a journalistic phenomenon crucial to understanding Colombia's present troubles.