This chapter introduces the Decision Theater (DT) methodology as a means to address complex, high-stakes decision-making scenarios in democratic contexts. Rooted in the historical interplay between theater and democracy, DT fosters iterative deliberation among stakeholders, policymakers, and scientists, enabling them to jointly explore potential interventions under uncertainty. By blending computational modeling, data visualization, and structured facilitated dialogue, DT supports participants in understanding the consequences of alternative policy paths while respecting diverse preferences and values. Two case studies illustrate DT’s adaptability: a retrospective look at the Cuban Missile Crisis highlights the importance of interdisciplinary informal deliberation, while contemporary efforts in Europe, China, and Hawaiʻi underscore the methodology’s scalability in environmental and socioeconomic domains. As an evolving decision support system, DT advances public engagement, fosters empathy, and harnesses scientific expertise without sacrificing democratic agency. The authors argue that such collaborative and computationally informed approaches are increasingly vital for mitigating systemic risks in the Anthropocene, especially given the ongoing, rapid decline of democratic values. By bridging science, society, and governance, DT offers a promising framework for inclusive collective decision-making.