In the context of the 'war on terror,' counter-radicalization (CR) policies are a form of security governance that uses social, cultural, and educational programs to preempt the future possibility of political violence. Based on a problematic understanding of 'radicalization' as the transition toward 'extreme' Islamic ideology, CR policies have principally targeted Muslim communities. As Muslim civil society organizations (CSOs) are enlisted to support counter-radicalization objectives, they have to balance advocating for Muslim communities - including raising concerns about anti-Muslim discrimination in CR policies - on the one hand, and on the other, acceding to participate in counter-radicalization initiatives. Employing a qualitative comparative approach, my dissertation shows how Muslim CSOs in Canada and the U.K. develop strategic responses to CR policy pressures. Data for this research are based on interviews with decision-makers at Muslim CSOs, policymakers, and informed individuals as well as analysis of policy documents and security practices related to counter-radicalization. I propose a conceptual framework that integrates theorization of power (Haugaard, 2012, 2021) with an organizational institutionalist model (Oliver, 1991), arguing that CR polices create relations of power between state institutions and Muslim CSOs, and responses of Muslim CSOs are best understood as contestations within these relations of power. My analysis reveals that, despite following different patterns of development, CR policies in Canada and the U.K. govern Muslims through racialized practices and notions of the "suspect community," risk, and preemption. Through CR policies, state institutions seek to produce compliant CSOs that unreflexively reproduce relations of domination. With the awareness of these dynamics, Muslim CSOs engage in sophisticated power contestations: 1) they make strategic choices about availing CR-related funding, cooperating with state security institutions, and responding to state institutions' withholding legitimacy for CSO activities, 2) they criticize state institutions for insufficiently including Muslim CSOs in the CR policymaking process and for ignoring the concerns of Muslim communities, and 3) they challenge dominant discourses in CR policies and demand more transparency about the knowledge basis for CR policies. This dissertation shows how, despite institutional constraints, CSOs can use their agentic power to engage in meaningful contestations toward emancipatory goals.