The conservation threat represented by invasive species is well-known, but the scientific opportunities are underappreciated. Invasion studies have historically been largely directed at the important job of collecting case studies. Invasion biology has matured to the point of being able to incorporating itself into the heart of ecology, and should be viewed as extensions or critical experiments of ecological theory. In this edited volume, global experts in ecology and evolutionary biology explore how theories in ecology elucidate the invasion processes while also examining how specific invasions informs ecological theory. This reciprocal benefit is highlighted in a number of scales of organization: population, community and biogeographic, while employing example invaders in all major groups of organisms and from a number of regions around the globe. The chapters in this volume utilize many of the cutting edge observational, experimental, analytical and computational methods used in modern ecology. Through merging conceptual ecology and invasion biology we can obtain a better understanding of the invasion process while also developing a better understanding of how ecological systems function.