To what extent do perceptions of public opinion effect individual support and political participation in political action? To what extent might media use moderate the role of public opinion in predicting political participation in the digital age? This study investigates these questions by analysing unique data from an experiment and a representative survey designed and conducted at the height of the summer 2011 protests in Israel. This study offers a new analytical model for studying activism by independently and simultaneously examining the direct and indirect effects of perceptions of majority support, individual support and media use on political behaviour. The experimental results suggest that perceptions of public opinion and media use did affect participation in the 2011 social movement. Specifically, increased perception of majority support for the movement led to increased rates of participation. Moreover, media use was inconsequential among those respondents who perceived that a majority of the public supported the protest. Digital media had a moderate effect on the association between perceptions and support for the protest movement, but there was no such effect with respect to mainstream media use. The findings provide new empirical insight into the effects of perceptions of public opinion and media use on political behaviour. In doing so, they help to explain the development of mass protest movements in the digital age and especially the potential effect of perceptions and media use in promoting the evolution of social movements as well as involvement in collective action in the digital age.