This study offers a comparative examination of desegregation policy reforms in Belgium, Chile, and the Netherlands, addressing equity reforms to universal school choice systems. Through an analysis of the reform trajectories, we explore the evolution of policies, the causal mechanisms of change, efforts to institutionalize policies, and the sources of resistance to reform. We then undertake a cross-national comparison to discern trends and confirm or disconfirm theorized causes. Policy strategies from each context included nondiscrimination policies, fiscal incentives, and eventually reform of admissions procedures. Causal mechanisms facilitating equity reforms included shifts in political context, grassroots mobilization, generated focusing events through scholarly work and reports of civil society and transnational actors, and effective framing. Oppositional forces from non-state school networks and middle-class/white parents emerged in each context, affecting reform design and the path to institutionalization, but were unable to block reforms. The resulting reforms in each context were the products of compromise that retreated from deeper structural changes, likely mitigating the effects of reforms on school-based segregation.