In this text, Thompson advances a new conceptual approach to the evolution of species interactions - the geographic mosaic theory of coevolution. Thompson demonstrates how an integrated study of life histories, genetics and the geographic structure of populations yields a broader understanding of coevolution, or the development of reciprocal adaptations and specializations in interdependent species. Using examples of species interaction from a range of taxa, Thompson examines how and when extreme specialization evolves in interdependent species and how geographic differences in specialization, adaptation and the outcomes of interactions shape coevolution. Through the geographic mosaic theory, Thompson creates connections between the study of specialization and coevolution in local communities and the study of broader patterns seen in comparisons of the phylogenies of interacting species.