This volume provides the first worldwide overview of Planning Support Systems (PSS) and of their application in practice. PSS are geo-technology related instruments consisting of theories, information, methods, tools, et cetera for support of unique professional public or private planning tasks at any spatial scale. The book desires to progress the development of PSS which are far from being effectively integrated into the planning practice. It provides an Internet-based worldwide inventory of innovative examples and successful applications of PSS in a number of different planning contexts. In depth insight into the purposes, content, workings, and applications of a very wide diversity of PSS is given. References to URLs where additional information can be obtained are very useful.