In today's society, it is very common for decisions that influence us all to be made by a combination of interested parties, all with their own agenda. In this instance, how can we be sure that the decision is the correct one, not just decided by the group with the most political influence or most money? Such groups have now become fundamental decision-making units within and between organisations in most societies and are more often than not very complex structures. The use of Geographic Information Systems (GIS) Groupware can be used in several practical contexts to make sure that spatial decision problems are overcome in the most effective way. A fundamental aspect of a spatial decision problem is the matter of location. The complexity of spatial decision problems result from the multiplicity of stakeholders involved, their often conflicting interests, and the intangible variables of the decision environment. Examples of such problems include: where to locate a public facility, which brownfield redevelopment strategy to choose, which sites to select for environmental restoration, or which comprehensive land use plan to adopt. Good solutions to such problems -if they exist at all- are characterised by a certain minimum level of secretarial support; hence the decision-making process should involve experts, citizens, and interest groups alike. Such a collaborative approach to spatial decision-making needs methodology, tools, and application examples to inspire its adoption and more widespread use. This book sets out the key to the collaborative spatial decision-making approach: its theoretical basis, the requisite tools, and a number of application examples. GIS professionals and researchers should find this an invaluable guide to an emerging area of GIS