Can countries and regional organisations develop effective and efficient Spatial Data Infrastructures (SDIs) or the technologies, policies and people necessary for the sharing of spatial data throughout all levels of government, the private sector and institutions? This book provides an overview of SDI policies, concepts, nature, standards and practices that are associated with the design, implementation and operation of an SDI. it sets out the similarities and differences between SDIs operating within and between different jurisdictions. It identifies key factors, including socio-political, economic and cultural factors, influencing the success of SDI initiatives, and introduces the concept of an SDI hierarchy based on hierarchical spatial reasoning. This book builds on an International Symposium on SDI held in Melbourne in November 2001, and contains re-written, expanded and more focused reviews of SDI developments. Many chapters are by leading professionals, researchers and practitioners in SDI development. The book presents a series of alternative long-term visions and identifies many of the forces for change. It is useful for both professionals and students in geographic information systems (GIS) and those involved in building and maintaining SDIs.