This book is for researchers, academics, and professionals with geographic information systems (GIS) experience who need to know more about environmental modeling. It is also intended for environmental modelers who want to know more about GIS, its advantages, and its problems. The first part of the book describes the state of the art in GIS, environmental modeling, spatial statistics, and spatial databases. The second part reviews the state of integration in each of the major "process" areas, ranging from atmospheric to subsurface. Each section includes an overview chapter and case studies. This book will be useful to planners in federal agencies (EPA, DOE, USGS, Parks Service, etc.), academic researchers, environmental consultants, and as a text for advanced GIS courses.