This is an open access book. What holds societies togetherâand what drives them apart? As worry over political polarization and social cohesion intensifies across the globe, this volume explores timely and vital questions of social cohesion and polarization through the lens of Computational Social Science. It brings together leading and junior scholars who harness the power of computational methods to analyze, model, and understand discourse, social relationships, and beliefs. Drawing on tools such as agent-based modeling, social network analysis, and natural language processing, the book offers a range of innovative approaches to study how belief systems form, attitudes polarize, and communities fragment. Aimed at researchers, students, and practitioners across disciplines, this volume is both an introduction to the field and a showcase of its most promising applications. It is an introduction into CSS of social cohesion and polarization, and an invitation to rethink how we studyâand perhaps even how we can repairâthe social fabric.