The past two decades have witnessed a growing interest in anti-gender movements across various domains including academia, politics, civil society, and in the broader public discourse. The inception of this doctoral thesis stemmed from the necessity to comprehend the emergence of antigender movements across diverse national contexts that share similar sociopolitical contexts. The lack of comparative research on anti-gender movements, especially within the same region, indicated a significant research gap in this field. Moreover, existing research on anti-gender mobilization has often overlooked the post-communist region, a region which has been systematically underexplored in the analysis of far right mobilization. Additionally, studies on anti-gender mobilization rarely relied on social movement theories and contentious politics. Therefore, the aim of this doctoral thesis is to explore the emergence of anti-gender movements in 11 post-communist EU member states using the political opportunity structure as the analytical approach and set-theoretic multi-method research as methodology. The main research question of this doctoral thesis is which conditions primarily account for antigender mobilization and its absence in post-communist EU member states for the period between 2004 and 2019. Through process tracing on individual conditions, followed by sufficiency analysis to identify combinations of conditions that are sufficient to bring about the outcome, austerity measures, the presence of far right parties, normative action, and the relationship between the Church and the state have been identified as crucial conditions in explaining the emergence and absence of anti-gender mobilization. As a supplementary research question, I explore how conditions contributed to the emergence and absence of anti-gender mobilization in post-communist EU member states. The results of the analysis indicate two primary pathways through which anti-gender movements emerge in postcommunist Europe: via the institutionalized far right and religious mobilization. The institutionalized far right plays a key role in explaining the presence of strong anti-gender mobilization in Hungary, Slovenia, Croatia, and Poland. On the other hand, religious mobilization, explains strong anti-gender mobilization in Romania, Croatia, and Poland. The diverse paths of the Croatian and Polish anti-gender movements suggest the potential for multiple simultaneous processes to culminate in the emergence of strong anti-gender mobilization. Simultaneously, the absence of strong anti-gender mobilization is linked to unfavorable political opportunities hindering the formation of anti-gender movements in the Czech Republic, Lithuania, and Latvia, while the secular context presents an obstacle to the development of a strong anti-gender movement in Estonia. Despite similarities in how the opportunity structure influences anti-gender movements, there is significant diversity in the mobilization efforts among different national movements, an aspect I explored as part of the second supplementary research question via protest event analysis. Antigender movements in post-communist Europe vary significantly in terms of their strength, frequency, types of protest activities, and the nature of their demands. During the period between 2004 and 2019, I documented a total of 86 anti-gender protests, 305 petitions, and seven referendums in the 11 post-communist European countries. Strong anti-gender mobilization is present in Croatia, Hungary, Poland, Romania, Slovakia, and Slovenia, while Bulgaria, the Czech Republic, Estonia, Latvia, and Lithuania experience weak anti-gender mobilization. Although anti-gender referendums were conducted in Croatia, Romania, Slovakia, and Slovenia, the presence of other types of protest activities varies significantly across countries. For instance, the Slovenian movement demonstrates less activity through protests and petitions, while the Slovak movement primarily focuses on petitions, contrasting with the Romanian movement, which emphasizes protest mobilization. Conversely, the Croatian anti-gender movement actively employs all forms of protest activities. Furthermore, while anti-gender referendums were not organized in Hungary and Poland, the Polish movement engages actively in both petitions and protests, whereas the Hungarian movement predominantly concentrates on petitioning. Additionally, anti-gender movements in post-communist Europe articulate different demands, with opposition to LGBTIQ+ rights being the predominant demand across many movements, particularly in Hungary, Romania, Slovakia, and Slovenia. In contrast, the Polish anti-gender movement primarily opposes reproductive rights, while opposition to the introduction of sex education in schools is the primary demand of the Croatian movement. An examination of the factors contributing to the emergence of the 11 post-communist anti-gender movements led to conclusions regarding the conditions shaping these movements, with the economic crisis identified as a key factor. Anti-gender movements simultaneously exploit disappointment with neoliberal capitalism to identify enemies and mobilize supporters, offering familialist policies as solutions, contradicting the previous economic stances of gender-traditional movements. Furthermore, the importance of far right extraparliamentary mobilizations in postcommunist Europe was confirmed, contrary to assumptions about the dominant presence of far right activities within the electoral arena, especially in post-communist Europe. The formation of alliances with far right parties through opportunistic strategies was also acknowledged, taking various forms such as cooperation and takeovers. Additionally, the close relationship between the Church and the state played a pivotal role in the emergence of anti-gender movements, highlighting the contemporary role of religion in post-communist societies, evolving from marginalization and resistance to active political participation, as part of a broader process of the republicization of religion in post-communist societies. Far right parties and the Church, as key allies of the anti-gender movement, exhibit interchangeability, with the presence of either actor being sufficient for the movement's emergence. This interchangeability is facilitated by a new type of connection between the Church and the far right, known as the Christian right present in post-communist Europe. Furthermore, the employment of political homophobia in post-communist societies was recognized, manifested through the systematic restriction of LGBTIQ+ individuals' rights by state and societal actors. The strength and mobilization success of anti-gender movements signify the establishment of a parallel civil society, within which far right mobilization aims to change the liberal-democratic framework. In essence, anti-gender movements, as part of the far right civil society, successfully use democratic methods to achieve non-democratic goals.