The media sector is vital to the quality of democracies, yet its products or services are often traded in commercial markets. In Latin America, media markets are usually dominated by only a few large commercial media companies. Regulation often dates back to the times of military dictatorships, while neoliberal reforms have later accelerated concentration tendencies and increased the emphasis on commercial logics. The current state of the media sector is increasingly criticized as posing severe limits to processes of democratic deliberation, illegitimately concentrating political power and complementing other forms of social exclusion. In the last few years, calls for democratizing media markets have been echoed in some countries by policy reforms in the broadcasting sector. This paper sketches the regulatory challenge of democratizing predominantly commercial and concentrated broadcasting markets in Latin America. I demonstrate that commercial diversification is a necessary but not sufficient condition for plural media markets. Furthermore, debates about democratization go beyond the commercial diversity of media channels and rather address the conditions of access to the public sphere. Against the background of recent legislation in Uruguay, Argentina and Chile, I identify a trend toward the promotion of non-commercial broadcasters. Although media regulation is partly modernized to account for democratic demands, the extent of the reforms differs greatly. As the democratization of concentrated media markets conflicts with the interests of commercial firms, such reforms are only to be expected where active social movements push for changes.