The development of radio broadcasting in Colombia has put this media at the top of the audience, penetration (99,9%), credibility and influence. Its investments have not been displaced to other media, as television or press.The concentration of broadcasting media by families and political-economic groups reflects the same two-party system of the Colombian society. Thus, while during more than one hundred years the Colombian State has been dominated by the traditional rightist parties -Liberal and Conservative-, the national broadcasting enterprise has belonged to leaders or economic groups deeply relationed with one of these political units. Industry and politics are the two factors that have brought to the broadcasting polarization in two big commercial channels: CARACOL -1inked to the Liberal Party, and RCN, to the Conservatives.