Unlike in neighbouring countries, Spanish radio stations were subject to a severe censorship regime for most of the twentieth century. After the end of the civil war (1939), General Franco’s regime issued regulations to control the press and radio. In the case of newspapers, the Press Act (1966) eased this surveillance, but such relief did not apply to radio broadcasting. However, in the second half of Franco’s dictatorship, some local stations and, especially, a nation-wide radio station (Cadena SER) tried to bypass restrictions set by the authorities. This article covers different initiatives, paying special attention to those developed by Cadena SER, which played a decisive role in liberalising information. To this end, journalists who played a key role in this transition were interviewed. As a result of this research, it has been observed that, despite the threats, disobedience was a constant from the 1960s onwards. Such disobedience was not always aimed at fighting the regime during this time of social change, but also responded to the broadcasters’ commercial strategies. It has also been found that certain authorities facilitated these activities through their personal influence.