The thesis is devoted to a micro-sociological analysis of "big" protests. Comparing Russian "For fair elections" movement with Ukrainian Euromaidan, I study how eventful identities, solidarities, and cultural representations that emerged in the course of the protests then developed and changed contributing to either socio-political change, or reproduction. I analyze dynamics of both the uprisings themselves and the dynamics of post-protest collective action. The first part of the text analyzes a phenomenon new to Russia: the politicized local activism that has emerged in the wake of the "For fair elections" protests. Urban activism in Russian has been rarely politicized; rather, it addressed "familiar", "close to home" problems and that kept distance from "politics". Anti-Putin rallies of 2011-2012 changed the landscape of Russian civic activism. Inspired by the experience of collective actions, protesters resolved to keep it going in their own neighborhoods, establishing local activist groups and tackling smaller-scale problems typical of apolitical activism, e.g., defending parks from deforestation and buildings from demolition, and working for improvements. However, activists attributed oppositional and "political" meanings to practices that had been rather apolitical before the protests of 2011-2012. Thus, my study revealed the significant eventful change in the political culture of Russian urban activism. At the same time, in many cases mass events lead to the intensifying of pre-existing political and cultural structures, cultures, identities and discourses. In the second part of the text I show that Euromaidan consecutively first weakened and then enforced the ethno-cultural and political split between Western and Eastern Ukranian citizens. While “Euromaidan” initially succeeded at creating a new civic identity that united the protesters, this identity failed to spread beyond the event. Paradoxically, the initial push for civic unity and inclusivity, when intensified, transformed into a tool of promoting exclusivity. The text is based on the analysis of in-depths interviews and focus-groups. The conclusions address the theoretical discussions within the eventful approach in social science, pragmatic and cultural sociology.