The increased influx of refugees and migrants to the EU in 2015 has been followed by a noticeable presence of online hate speech against migrants in many countries across Europe. The article presents the results of a study of hate speech proliferation on Facebook in the Czech Republic during the summer of 2015. Its goal is to identify the producers of hate speech and determine their social background, explore the main channels of hate speech proliferation, determine the specific groups of migrants targeted by hate speech, put the hate speech in the context of online political communication, and discuss the role of media and politicians in the process of hate speech proliferation. With regard to the works of Castells, Skocpol or Bennett and Segerberg, online hate speech can be perceived as an extreme variety of new, rapidly evolving modes of political communication as such. Social and political activism has been shifting from membership-based organizations and parties towards flexible movements and initiatives with strong emphasis on the logic of identity politics. People may or may not engage in hate speech production as lone independent actors, but they still perceive their actions as part of larger collective efforts. When we focus on hate speech as a form of civic activism or networking, new interesting patterns can emerge.