Protest activity has become a central means for political change in Chile. We examine the association between social media use and youth protest, as well as mediating and moderating mechanisms of this relationship, using survey data collected in Chile in 2010. We found that Facebook use was associated significantly with protest activity, even after taking into account political grievances, material and psychological resources, values, and news media use. The link between overall Facebook use and protest activity was explained by using the social network for news and socializing rather than when it was used for self-expression. Postmaterialist values and political ideologies were not found to moderate the association between Facebook use and protest.