Fifty years ago, Mexico was the scene of a massive rock festival that marked a before and after for this musical trend in the country. Although neither the organizers nor those attending the Avándaro Festival came with political motivations, the rejection of the authorities and a good part of the public opinion of the time ended up marking and pigeonholing this movement. Between the late 1960s and early 1970s, Mexico was immersed in deep social conflicts, such as the 1968 student movement and the repression on the so-called Corpus Christi night in 1971. Avándaro is considered the Mexican Woodstock. In Aristegui, Federico Rubli, co-author of the book “I was in Avándaro”, explains what that megaconcert of Mexican rock meant and the teachings that it leaves today.