This book explores Orlando Fals Borda’s trajectory as a pioneering Latin American sociologist, highlighting how his life, political commitments and methodological inventions helped to re-found social science from the standpoint of peasants, popular sectors and the Colombian Caribbean. It foregrounds key themes such as feeling-thinking (sentipensar), participatory action research (PAR), and the peasantry as a historical subject, showing how Fals Borda wove rigorous theory, artistic narration and militant research into a single praxis oriented towards social transformation. The chapters trace his biography, his work on violence, agrarian reform and the “double history” of the Caribbean coast, while also reconstructing his methodological work on longue durée, subversion and utopia as tools to understand and change unequal, dependent capitalism. The book will be of particular interest to scholars, students and activists in sociology, social work, political science, history and Latin American studies, as well as to those engaged in critical pedagogy, decolonial thought and community-based research. It offers a rich resource for researchers, educators, social leaders and social movements seeking conceptual and methodological tools to link knowledge production with collective action and the struggles of rural and urban popular classes.