While much recent social science and humanities work has been a revolt against simplification, this volume explores the contrast between simplicity and complexity to reveal that this dichotomy, itself, is too simplistic. John Law and Annemarie Mol have gathered a distinguished panel of contributors to offer - particularly within the field of science studies - approaches to a theory of complexity, and at the same time a theoretical introduction to the topic. Indeed, they examine not only ways of relating to complexity but complexity in practice. Individual essays examine complexity from a variety of perspectives and cover an array of case studies and topics that include market behaviour, medical interventions, aeronautical design, the governing of supranational states, ecology, road-building, meteorology, the science of complexity itself, and the psychology of childhood trauma. Other topics include complex wholes (holism) in the sciences, moral complexity in seemingly amoral endeavours, and issues relating to the protection of African elephants. With a focus on such concepts as multiplicity, partial connections, ebbs, and flows, the collection includes narratives from Kenya, Belgium, Great Britain, Papua New Guinea, the Netherlands, and France, written by anthropologists, economists, philosophers, psychologists, sociologists, and scholars of science, technology, and society.