Why do some networks foster cooperation while others fuel extremism? How does trust evolve across cultures, institutions, and belief systems? And how do these dynamics play out in both offline and online worlds? In Trust and Networks, Sean F. Everton draws on insights from social network analysis, experimental research, cultural evolution, and other theoretical traditions to explore the nature of trust. From interpersonal relationships to nation-states, Everton explores how trust-and its absence-shapes human behavior. The first part examines the cultural underpinnings of trust, tracing its development through kinship, religion, markets, and norms. The second half focuses on how trust flows through networks, enabling (or hindering) influence, collective action, and the diffusion of ideas-including harmful ones, like conspiracy theories and radical ideologies. Featuring real-world case studies such as the Peoples Temple and QAnon, alongside discussions of nationalism, social capital, and online mobilization, Trust and Networks equips readers with the tools to understand and map trust in an era of polarization and digital connectivity.