Book excerpt: What is the urban–rural interface? Is it a visual phenomenon, a place where country gives way to neighborhoods and shopping areas in a startling way? Is it a simple factor of population density? There is nothing simple about the urban–rural interface—editors David Laband, Graeme Lockaby, and Wayne Zipperer present the broad spectrum of interdisciplinary complexities at play. Organized into three sections on changing ecosystems, changing human dimensions, and the dynamic integration of human and natural systems, this book is a must read for anyone who works in the real world, where natural and human systems are joined. This is the new sustainability science, an emerging discipline that integrates social and economic values with the physical, chemical, and ecological functions of ecosystems. The goal is optimal management, since our human impact is often significant and far-reaching in both space and time.